In this paper, a controlled sinusoidal signal generator (CSSG) based on the direct digital synthesize (DDS) chip-AD9851 is introduced. The CSSG is controlled by MSP430F4250, which is an ultralow-power microcontroller. The micro control unit (MCU) receives 4-20mA current provided by a current transmitter and then computes the frequency value of the input signal. A frequency value is converted to frequency words which are sent to AD9851. Through an amplifier, a sinusoidal signal can be obtained. With changing the value of input current, sinusoidal signal with different frequency value can be generated. Experiments indicate that the system can produce the sinusoidal signal with frequency 1MHz to 2MHz and accuracy 1Hz.