Abstract: According to the survey results of the live loads on floors of some multi-storey and high-rise residence buildings in Xi’an city and Baotou city, a statistical analysis on the equivalent uniform live loads on floors is performed, and then the reliability of the designed reinforcement concrete floors is investigated. A new factor called the minimum loads-supporting area ratio is proposed to take into account the least favorable distribution of live loads. Analysis results show that the equivalent uniform live loads cannot reflect the main features of live loads on floors of residence buildings, and further research work may need to be carried out; the minimum loads-supporting area ratio should be taken into account because it has great influence on the equivalent live loads on floors and floor reliability; the reliability level of floors of the residence buildings are high enough according to the present national codes, even subjected to the least favorable distribution of live loads.