The composition and pyrolysis performance of four kinds of feedstock were studied by using analytical instruments and pyrolysis furnace simulation experimental apparatus. Feedstock 1 is hydrocracking tail oil from domestic petrochemical enterprises, feedstock 2 is hydrocracking tail oil containing diesel oil from joint-venture petrochemical enterprises, feedstock 3 is hydrocracking tail oil containing diesel oil from domestic petrochemical enterprises, and feedstock 4 is diesel oil from domestic petrochemical enterprises. The experimental conditions of pyrolysis reaction are as follows: the outlet temperature of pyrolysis furnace is 780～820 ℃, the outlet pressure of pyrolysis furnace is 0.08 MPa, the residence time of pyrolysis furnace is 0.24 s, and the water oil ratio is 0.8. The results showed that the order of the yield of ethylene, propylene and butadiene was as follows: feedstock 1 > feedstock 2 > feedstock 3 > feedstock 4. The order of the economic benefit of the four kinds of feedstock are as follows: feedstock 1 > feedstock 2 > feedstock 3 > feedstock 4. Comprehensive evaluation shows that it is a feasible method to use the mixed feedstock (feedstock 2 and feedstock 3) of hydrocracking tail oil and diesel oil as the cracking feedstock under the conditions of existing industrial plants.