Requiring schoolgirls to wear skirts as part of their uniform reinforced gen der stereotypes and restricted movement, the Equal Opportunities Commission said.
Dr Priscilla Chung Ka-tak, gender director of the commission, said a code of practice urging schools to give students more choice was being drafted.
The code, which will not be compulsory, is the second to be drawn up by the commission.
Dr Chung said girls should be allowed to wear trousers.
'Traditional uniforms reinforce stereotypes and restrict movement because they can't move freely in a dress or cheong sam. They must be genteel, sit and behave properly - this is a typical example of gender stereotyping,' she said.
Dr Chung said some parents had lodged complaints and wanted the commission to change the situation.