R1234ze (E) is regarded as one of the competitive candidates of refrigerants. However its flammability has not been detected out completely. This paper contributed to the fundamental flammable characteristics and influences of R1234ze (E) as well as its blends by mixed with refrigerant R161 (fluoroethane) and R152a (1,1-difluoroethane) theoretically and experimentally. Firstly, the possibility of using R1234ze (E) as a refrigerant was analyzed by means of a technical review. Secondly, the flammability limits of pure R152a, R161 and R1234ze (E) were tested out respectively basing on a new built experimental rig. Continued, the flame image of R1234ze (E) was presented, and which was obtained under the testing condition of higher relative humidity of the surrounding air. In addition, the influence reasons of the relative humidity on the flammability limits of refrigerants were analyzed. Finally, the flarnmability limits of R1234ze (E)/R161 and R1234ze (E)/R152a were tested out under the different concentration ratios. The results showed that R1234ze (E) possessed a slight flame suppression effect on both R161 and R152a but could not make it unburnt completely under the experimental concentration range. And the flamthability limits can be estimated by some a third order polynomial with acceptable accuracy. (C) 2015 Elsevier Ltd. All rights reserved.