Oil cracking gas plays an important role in the resources of natural gas in the basins with high and over mature marine source rocks in China. The prediction of the oil cracking gas resources becomes necessary and urgent in the gas exploration in these basins. A marine crude oil sample was pyrolyzed using sealed gold tubes system. The pyrolysates including gas, liquid and solid were quantitatively analyzed. Based on the pyrolysis data and kinetic calculation, the yield correlativity among gas, liquid and solid products was regressed with high correlative coefficients to establish a prediction model suitable for the resource estimation of oil cracking gas. The verification formula for this model was also established on the principle of mass conservation. The affecting factors and the application preconditions of this prediction model were discussed. This model would enlighten and provide some new ideas for the resource assessment of natural gas in the high and over mature marine carbonate source rock areas in China. It is expected to be valuable in gas exploration.