The dynamic characteristics in lightning discharge plasma channel are of great significance in studying the micro-physical mechanism of the discharge process. This paper established a simplified radiation-hydrodynamic model (SRHM) of the return stroke channel radial expansion based on the fluid dynamics theory and the time evolution characteristics of the light radiation power observed by experiments. The influence of current waveform on the dynamic characteristics of return stroke channel was investigated, and the temporal evolutions of the characteristic parameters, such as temperature, pressure and expansion speed for return stroke channel were analyzed. The results indicated that the current peak value and the risetime are important factors in determining the channel dynamics characteristics. At the initial stage of return stroke, the light radiation loss has a distinct influence on channel temperature, which leads to a transitory drop in temperature forming a bimodal waveform structure. Following the peak current, the channel reaches peak pressure, which leads to a subsequent secondary temperature peak and accelerates the expansion of the channel. Large peak current and the rise time are the indicative parameters of strong discharge and the main factors leading to lightning disaster. This work provides reference data for further research on the radial energy transport of lightning return stroke channel and the formation mechanism of shock waves.