The move comes despite the children facing an hours-long commute to and from school each day - something that puts off many parents.
Schools in North district, where commuting is easier, have little trouble filling their classrooms and even struggle to accommodate pupils from nearby Shenzhen.
But with Hong Kong's low birth rate leading to falling enrolments, those elsewhere without enough pupils face closure.
Yesterday schools in old urban areas further south such as Pokfulam and Chai Wan - at the far western and eastern ends of Hong Kong Island - were chasing potential entrants in Shenzhen. The schools are among more than 20 Hong Kong kindergartens, primary and secondary schools attending a three-day exhibition in the border city this weekend to promote themselves to parents with Hong Kong-born children living on the mainland.
The fall in pupil numbers will affect secondary schools the most in the next few years.
Reports Education Post.
Commentry from Steven Corry, Brtish Council
While Hong Kong elementary schools recruiting students from across the border in Shenzhen does not have any ramifications for student recruitment or TNE for a number of years, this is a sign of things to come. As with Mainland China, Hong Kong faces a future decline in student numbers due to simple demographics. Students who enter the Hong Kong system at primary level would however be expected to remain in the Hong Kong system at higher levels, potentially maintaining numbers. Likewise, for TNE provision in Hong Kong, market demand may be maintained if and when the relevant Hong Kong and Mainland China authorities allow Mainland students to study non-local courses.