An asynchronous distributed sequential fusion algorithm was proposed for the asynchronous measurements which were measured by the networked optic-electronic tracking devices. The asynchronous distributed sequential fusion algorithm was composed of a local estimator and a fusion estimator. First, by using the state transformation method, the asynchronous measurements obtained by a sensor node was aligned to the fusion instant to get the pseudo-measurements. Then, a local sequential estimator was developed with respect to the pseudo-measurements and the target motion model to calculate the local estimation, by using orthogonal projection. Subsequently, by modifying the covariance intersection algorithm, a diffusion-based fusion estimator was designed to fuse the local estimation in the neighborhood. The simulation results of a target tracking system validate the effectiveness of the proposed target tracking algorithm.