A rubber detection system for rubber raw material includes a controller, a rubber sampling module, a rubber calender, a temperature control module, a mooney sensor, a power meter, an expansion ratio detection module, a rotation counter, and a specific gravity detection module. The rubber sampling module obtains a rubber to be tested consistent with a weight value. After the temperature control module determines that the rubber to be tested has reached a temperature value, the rubber calender outputs the rubber to be tested having a thickness value. The power meter records and obtains a power consumption value form the rubber calender. The expansion ratio detection module obtains an expansion ratio based on the thickness value and a roller spacing. The rotation counter obtains the number of rotations of the rubber calender. The specific gravity detection module obtains an actual specific gravity value of the rubber to be tested.