The invention provides a method and a system for two-point injection type modulation of a transmitter in a data set, wherein the method comprises the following steps of: generating a phase signal through a digital signal with the need of modulation; generating a varying frequency signal by the phase signal; generating a fixed frequency signal through a control signal; and performing amplitude decreasing for the varying frequency signal and performing carrier-frequency output for the fixed frequency signal. According to the method and the system, frequency can be changed just by changing a reference voltage, consequently, a range of settable frequency is large, and a range of application is wide; and by means of generating the varying frequency signal through a voltage-controlled module, difficulty in debugging is low, implementation is easy, influence of a high-frequency Q value is low, and product consistency is high.