Aiming at the problem of simultaneous measurement of particle size and quantity,on the basis of Mie scattering theory,an optical sensor which can measure the size and quantity of particles in real time is designed by combining the angular scattering particle counting method and the small angle forward scattering method.Based on the photocurrent range collected by the photodiode,an amplifier circuit with a signal to noise ratio of 51.8 dB is used to sample the current to achieve higher counting efficiency.According to the relationship between the scattered light energy distribution and the particle size,the objective function is derived,and the long beetle algorithm is introduced to optimize it.The experimental results show that the concentration measurement data of the sensor is highly consistent with the actual concentration value change trend,with a correlation above 0.99,a relative error within 10%,and a low particle size inversion error.Thus,the utility of designed particle sensor system is verified.