Zonal Safety Analysis (ZSA) is important to system safety analysis, and is especially required during the development of aircrafts. As the ZSA method in present specifications and standards is not well-enough designed to implement, an improved ZSA scheme was put forward here. In the new scheme, the connotation of ZSA method was clarified, and the method was made more practical in the field of engineering. Firstly, a universal set of zonal hazard factors was defined, which set boundaries for analysis of hazard factors and the hazards inside the selected zone. Secondly, hazard sources which include energy factors, product failures and hazard induced by coupling among those hazard factors in a complicated system were analyzed. Thirdly, risk of zonal hazard was comprehensive assessed to formulate rules for safety design and operation. The improved ZSA method could help to get accurate analysis result and enhance safety of products, which was illustrated by the undercarriage bay on aircraft CRJ200.