John Gittings in Beijing

It is always worth looking in at the Beijing art gallery, near the Forbidden City, for a glimpse of China's changing values. The admission is only four yuan (30p), a reminder of the time when culture was for the masses. On a Saturday morning, several Chinese families are exploring the past.

They have plenty of room from which to survey the canvasses - these days the gallery is much less popular than the shopping malls down by the Avenue of Everlasting Peace.

"In those days the artistic level was not so high", says an older visitor as we study a heroic group of workers, dwarfed by the metal structures of the Daqing oilfield.

"Then we wanted to show the efforts of labouring people to build socialism. Now we are more interested in aesthetic quality."

A classic 1964 picture shows Chinese visitors in front of the Chairman Mao portrait in Tiananmen Square. It was turned into a poster which sold millions of copies. The perspective is deliberately flat and the figures pose as if for a photograph, sailors to the right, national minorities to the left, and cheerful villagers in their best clothes at centre.

Women were more prominent in those revolutionary days. In They are Growing Up, three young women try to identify a blade of wheat with a magnifying glass and a textbook. "They must have been students who were sent down to the countryside," explains another helpful visitor.

Such images belong to a different visual world from today's, where women feature most prominently in lingerie advertisements.

In the 1980s the gallery was the scene of two famous challenges to the establishment. I remember catching the Stars exhibition in August 1980. Huge crowds still wearing Mao jackets peered in dim lighting at nudes, abstracts and surrealist paintings.

"I can't understand this picture. All I can see are some colours leaping about," one visitor complained. "You have understood it correctly," replied the deadpan artist.

In 1989 - on the eve of the Tiananmen Square demonstrations - I missed a much more avant-garde exhibition when condoms were thrown on the floor and one artist fired a pistol at her own work because she said it "lacked destructive energy".

Several pictures today illustrate the tension of those years when political as well as artistic convention was challenged. The exhibition is dominated by Father, a super-realistic canvas painted in 1980 by Luo Zhongli showing the sweaty head and lined face of a peasant - symbolic of China's failure to tackle rural poverty. (Luo was told to add a ballpoint pen behind the peasant's ear to make him look more "modern").

A picture by Chen Haiming of young men and women huddled against the cold in a log cabin is titled Our Generation (1984). It recalls the hundreds of thousands of young people sent to do manual labour during the Cultural revolution (1966-76).

Experimental and performance art is no longer a sensation in the new private galleries of Beijing and Shanghai. Much new art has become closely tied in to the international market, losing its Chinese identity.

In the antique markets, I am offered old posters of the Cultural revolution for prices between 400 and 1,000 yuan (£35-£85). The dealers tell me they would cost twice as much in Hong Kong.