As we all known, marine source rocks distribute widely in China, which have old geological time, large burial depth and high maturity. When they reached at the critical hydrocarbon-generating temperature, the carbonate source rocks begin to generate hydrocarbon again. The secondary hydrocarbon generation means that source rocks renew hydrocarbon generation when their temperature is higher than that of the primal hydrocarbon generation and reach the limited temperature of secondary hydrocarbon generation. The main generating materials include kerogen, dissoluble organic matter, inclusion organic matter, crystal-enclosed organic matter, solid bitumen, adsorbed organic matter from primal hydrocarbon generation, stylolite organic matter and etc. Whether the primary maturity is up to the corresponding maturity that the primal hydrocarbon generation reach peak or not, the secondary hydrocarbon generation always has a relative hydrocarbon generation peak. There are some divarications on the critical problems of the secondary hydrocarbon generation, including amount, evolution route and generating start. It is suggested that the theory research should be strengthened upon the thermal simulation experiments, chemical dynamics and numerical simulation.