When Choh H. Li retired from his job as research director at Honeywell Inc. in Minneapolis, after working there for 37 years, he came to Taiwan's new science-based industrial park planning to stay for just three years.

Almost eight years later, the park - known locally as Taiwan's Silicon Valley - has already outgrown itself.If Mr. Li's ambitious plans to expand it into a technopolis work out, he'll be here a while longer. And if his agenda is successful, many scientifically trained Taiwanese working abroad will be returning home.

The park at Hsinchu, about 60 miles southwest of Taipei, was meant to attract high-technology investment. It houses 70 local and foreign companies, including American Telephone & Telegraph Co. and Wang Laboratories Inc.

Its residents turned out a total of nearly US$900 million worth of computer and telecommunications products in 1987, almost double the 1986 figure.

With nearly 1,000 acres of land already filled, Mr. Li, now its director general, is looking for an additional 1,000 acres, which he hopes to develop by 1996.

But if the science park is to take off, a lot more people will also be needed. Employment needs within the park are expected to jump to 20,000 by the end of this year from the present 12,000. By 1996, the figure may reach 70,000 to 80,000.

Hsinchu is a small town that has traditionally seen most of its young people head off to Taipei in search of better career opportunities. The city has a population of 300,000 and has seen almost no growth over the past 30 years. Growth for the next 10 years is projected to be only 10,000.

I need so many things - more people around the area and more contractors to supply the park with odds and ends, Mr. Li said.

By 1996, we will need a total population of 1.2 million in this area, and that is why the concept of a science city came about.

The plan calls for construction of two new cities in addition to the original Hsinchu, which dates back to the Qing Dynasty (1644-1911).

The cities are to have all the conveniences of major international metropolitan areas. The goal is to attract people back from the United States - and keep them here.

If there is a second brain drain, Taiwan is done for, said Mr. Li. I want to create an attractive environment for people here.

There are some 23,000 students from Taiwan studying in the United States, the largest foreign contingent there, and it is estimated that 85 percent didn't return home in the past, although there are indications that is now changing.

There are an estimated 300 returnees working in the park now. More than half the companies there were set up by returnees with doctorates earned abroad, primarily in the United States.

Productivity is high - three times higher than outside the park - with per capita production of US$77,000 last year. That is comparable to Silicon Valley, but at much lower labor costs.

Mr. Li obviously is influenced by his own time in the United States.

Visitors to the park are shown his future science city - called Riverfront Town - which Mr. Li likens to the Charles River area in Boston, but with a San Francisco-style Fisherman's Wharf and a romantic Hilltown.

Estimates put the cost of just one new city at about US$1.5 billion, with 10 percent to 15 percent of the funds coming from government and the rest from private developers.

At the same time, great care is being taken to preserve historical sites in the old city while it is expanded. I want to preserve the old town, said Mr. Li. The old and the new have to live together in harmony.

His plan has won the support of the central, Hsinchu and county governments. The centralgovernment is considering making it the nation's 16th key project and the county administration said it will move its headquarters to Riverfront Town.

Premier Yu Kuo-hwa, who presented the project to Parliament, says US$250,000 has been allocated by the central government for a feasibility study of the park. One park official hints that approval is already assured.