A preparation process of ethylene by using ethane cracking process is characterized by that its raw material gas includes ethane or refinery gas, it is mixed with oxygen gas or air and inert gas, andthe ethane in the raw material gas can be selectively oxidated into ethylene, its reaction temp. is 700-900 deg.C and reaction pressure is 0.01-1.0 MPa, the retention time of reaction gas is 0.6-3.5s, and the mole ratio of C2H6/O2 is equal ti 0.8-4, and its inert gas content is 10-80%. Said invention changes the heat-absorbing reaction of ethane thermal cracking reaction into heat-generating reaction so as to reduce energy consumption, and at the same time, it can obviously raise ethane conversion rate and ethylene yield, and can use the regulation of oxygen introduction to overcome the coking phenomenon which may be produced in the course of reaction.