Traditional VGA is not suitable for biomedical applications because of its low linearity. In this paper, the traditional structure based on programmable transconductance was analyzed, and the relationship between loop gain and distortion was obtained. Based on this, a new type of VGA based on programmable transconductance was designed, which improved the linearity of VGA. The simulation results showed that the current consumption of the circuit was 10 μA at 12 V supply voltage and 0~30 mV input signal amplitude range. The total harmonic distortion of VGA was less than 05%, the IM3 was reduced by 14 dB, the IIP3 was 1857 dBm, and the equivalent input noise was 616 nV in the range of 01 Hz to 100 kHz.