Soil radon measurement of high stability and sensitivity is widely applied, and in some applications, such as in uranium prospecting, ²²²Rn should be distinguished from ²²⁰Rn. To meet this requirement, a practical method based on soil radon diffusion and accumulation theory to measure soil radon by Alpha Particle Spectroscopy (α-PS) is discussed in this paper. The α-PS measurement method can effectively overcome the effects of ²²⁰Rn and its daughters (²¹⁶Po, ²¹²Bi, ²¹²Po). The system can eliminate the impact of soil radon field disturbance and non-uniformity through soil radon static diffusion. Radon daughters (²¹⁸Po, ²¹⁴Po) are accumulated under the action of an electrostatic force, which not only enhances the measurement sensitivity, but also increases robustness of the measurement. Simultaneous measurement of multiple points can increase the comparability of measurement data and the measurement efficiency. Experimental data shows that the soil radon measurement method was robust. So it has wide applications such as in geological prospecting, in fissure groundwater exploration and in ground subsidence inspection.