Abstract: Passive radar imaging algorithm based on external illuminator requires large accumulated rotating angle of target. But in an actual circumstance, large rotating angle demands long time， which is hard to satisfy the request of real time，on the other hand，target reflectivity function differs at various aspect angles，Moreover， when rotating angle increases，target reflectivity function differs seriously. In this paper, an ESPRIT based high resolution passive radar imaging algorithm is proposed to solve the problem which is that how to form a good image at the instant of small rotating angle. In the method self-correlation matrix of the returned echoes is estimated firstly，then corresponding sine wave frequencies of the scattering-centers with the object is determined through eigenvalue decomposition，target location is deduced with the sine wave frequency，hence the reflectivity of the scattering-centers are computed. Computer simulation confirms the feasibility of the algorithm.