Abstract: The generalized short-circuit ratio is a static index which reflects the influence of the interconnection of multiple power electronic devices and the strength of AC power grid on the system oscillation,which can be used to quantify the small signal stability margin of the system.The randomness of renewable energy power generation in multi-infeed system causes the uncertainty of small-signal stability margin.Therefore,aprobabilistic stability evaluation method of small disturbances for power electronic based multi-infeed system based on generalized short-circuit ratio is proposed.Firstly,the generalized shortcircuit ratio under rated operating conditions is extended to generalized operation short-circuit ratio under general operating conditions to evaluate the small-signal stability margin when the power electronics equipment output arbitrarily power.Secondly,because of the generalized operation short-circuit ratio corresponding to the minimum eigenvalue of the admittance matrix in mathematics whose elements contain uncertain output power,the matrix probability D stability problem is used to describe the stability assessment of small disturbance probability systematically.At the same time,in order to overcome the difficulty of obtaining the accurate power output probability distribution in engineering practice,the expectation and variance of probability are used to describe the random information,based on which,the matrix probability D stability problem is transformed into semidefinite programming problem,which is easy to be solved with generalized moment theory.At last,an example is given to illustrate the effectiveness of the proposed method.