Traditional voltage stability analyses of AC/DC hybrid systems are mostly based on deterministic methods, without taking into account the influence of various uncertain factors, this will do harm to the economy and rationality of system operation. In order to make up the deficiency of deterministic analysis method, this paper proposes a voltage stability analysis of AC/DC hybrid systems based on two-point estimate method. The method takes into account the uncertainties of load levels and power growth factors and establishes the loading margin model of AC/DC hybrid systems. The first three statistic moments of loading margin and bus voltage on the point of voltage collapse are computed by a few deterministic computations, thus the probabilistic distributions of the desired variables are obtained and the probability of voltage instability under some load level is determined. Compared with Monte Carlo simulation, the computational accuracy is satisfied and the execution time is significantly shortened.