More than half the catering and entertainment businesses surveyed fear round-the-clock opening of the border crossing would lure away customers and reduce profits.
But the transport and import/export sectors appear to be more bullish, with one in four expecting improved income as a result of the move.
Officials say the overall impact could be positive.
The government and mainland authorities have agreed to introduce the long-awaited 24-hour passenger crossing at Lok Ma Chau on January 27.
The Central Policy Unit, a government think-tank, commissioned studies to assess the impact on businesses and households with surveys covering 14,244 people and 1,598 firms.
More than half of the restaurants, bars, karaoke lounges and massage parlours believed their profits would be reduced - with possible job losses - after 24-hour crossings started.
