The invention provides a multifunctional oil soluble complexing agent for hydrocracking of a high-sulfur poor-quality heavy oil slurry reactor. The multifunctional oil soluble complexing agent comprises oil soluble liquid catalysts having hydrogenation and coke inhibition functions for the hydrocracking process of the high-sulfur poor-quality heavy oil slurry reactor, vulcanizing agents with a metal vulcanizing function and coke inhibition agents with a reactor wall coke inhibition function. The oil soluble liquid catalysts are composited by one or more of metal naphthenates of group VIB and group VIII in a periodic table of elements, the vulcanizing agents refer to elemental sulfur and carbon disulfide, and the coke inhibition agents refer to oil soluble organic compounds and are mixture of one or more of cationic surfactants, anionic surfactants, fatty acid and fatty amine. The multifunctional oil soluble complexing agent is simple in dispersing process in heavy oil raw materials and is capable of effectively inhibiting reacting green coke quantity and coking of the reactor wall, hydrocracking conversion rate of the high-sulfur poor-quality heavy oil slurry reactor is increased, and operating cycle of a device is prolonged.