In liquid-crystal phased array, the actual wavefront may deviate from the ideal wavefront, since the actual performance depends significantly on voltage quantization, phase sag, fringing effect, the manufacturing process of liquid crystal device, and so on. Thus, to meet the requirement of beam scanning in the view field, the voltage is constantly adjusted according to deviation between the actual wavefront phase and the ideal, such that the actual phase can approximate to the ideal phase as much as possible. This has been one of the key problems in liquid crystal phased array. For retrieving the phase in liquid crystal phased array, a novel output-plane-based phase retrieval algorithm with wavefront iteration is presented. Specifically, the wavefront phase distribution is retrieved by using the knowledge of intensity measurements in three output-planes. Compared with the algorithms depended on the two output planes, our algorithm can achieve high precision. Moreover, the algorithm exploits angular spectrum transfer function, thus the results are more reliable. The theoretical analysis and simulation experiments indicate that this algorithm enjoys advantages in terms of precision and efficiency simultaneously.