Time difference of arrival (TDOA) continuous localization is a challenging area because the need of intermediate variable for traditional localization model. Aiming at solving this difficulty, a TDOA localization model in three-dimension (3-D) space which relates only to the target state is derived and then based on it, a weighted instrumental variable (WIV) algorithm is proposed which uses the pseudo-linear estimation (PLE) solution to evaluate the suboptimal WIV matrix and yields a closed-form, consistent and asymptotically unbiased solution. Simulation results validate the superior performance of the proposed WIV algorithm compared with several typical algorithms.