In order to provide an accurate emission light source to the atomic magnetometer for magnetocardiography measurement, a new type of stable laser source control system is proposed to ensure that the laser can output at a constant power and a stable frequency. A precise temperature control system is designed to maintain a reliable temperature range. The effectiveness of the system is verified by experiments. The results show that the power drift value and wavelength drift value are 1.2 μW and 0.9 pm, respectively, which meet the requirements of system stability and accuracy.