This article starts with the research results that the performance of the ethylene production from hydrocarbons cracking is linked not only to the distillation range of the hydrocarbon distillate, but also its components. It raises a new concept of expanding feedstock sources different from the global trend of using lighter feedstock. The heavy distillates of Daqing crude, such as the third cut of the atmosphere tower, the first cut of the vacuum tower and the sweat distillate which is the by-product of the de-waxing of the vacuum second and third cuts, can be used as feedstock for ethylene units. This article summarizes the performance tests of the feedstock, the evaluation in a simulated cracker and the application results on industrial units. It proves that the feedstock ensures high ethylene yield and longer service lfie of cracker, thus is of obvious economic benefits.