The invention belongs to the technical field of a radar and discloses a target micro-motion parameter estimation method based on broadband radar phase ranging. The method comprises the following steps: determining a cosine expression of an included angle formed between a radar sight line and a symmetry axis of a rotational symmetric target; determining an observation distance matrix X=R+A+W of all scattering centers in radar domain frequency echo signals on the radar sight line; carrying out singular value decomposition on X-A to obtain a (2*M)-dimensional Euclidean reconstruction matrix CE of a radar viewing-angle matrix, the (2*M)-dimensional Euclidean reconstruction matrix CE and a (2*M)-dimensional radar real viewing-angle matrix C meeting a relation C=OCE; and constructing an objective function (the relational expression of which is shown in the specification), and calculating an optimization expression (shown in the specification) to obtain target micro-motion parameters to be estimated, such as Wp, phi0, theta and gamma. The method can solve the problem that target micro-motion parameter estimation can be carried out under a premise of knowing priori information of a target shape.