The invention discloses a signal transmission method based on mud pulse pressure amplitude. The signal transmission method is characterized in that the pressure amplitude is set to be in a ten-level decimal form, and is uniquely and correspondingly represented by a number of 0-9 in sequence; and the lowest pressure amplitude indicates 0, and the highest pressure amplitude indicates 9; and the downhole data is transmitted in a decimal form, and after receiving the decimal data, the surface decodes the data to complete the transmission of the downhole data. Compared with a current method of transmitting signals with fixed amplitude pulse, the utilization rate of the pressure signal is significantly improved, the coding strength is reduced to a certain degree, the data transmission efficiencyis significantly improved, meanwhile, with the further improvement of the sensing accuracy of a pressure sensor, the utilization way of the pressure signal amplitude can further be widened, and the transmission efficiency can be increased simultaneously.