Abstract: In order to study the radiolysis effect of α particles to salt-free reagent, the α dose rate of α source needs to be determined. The α dose rate of ²³⁸Pu solution was detected by the Fricke dosimeter, the dose rate of per unit concentration of ²³⁸Pu was 40.0-43.1 Gy•L/(g•min). Calculated by the energy of α particles emitted by ²³⁸Pu, the absorption energy of ²³⁸Pu solution is 32.58J/min, which is 32.58 (Gy•L)/(g•min). The experimental deviation is about 23%-33% which is related to the experimental environment and the difficulty of α-determination.