Aiming at the problems of the current TDOA (Time Difference of Arrival) unit positioning system of ultra-wideband, such as multi-solution of position and low positioning accuracy. In this paper, a cooperative positioning method of adjacent units and a cooperative positioning equation solving algorithm based on improved salphus swarm algorithm are proposed. In this method, by summarizing all the measured values of the same positioning request signal received in adjacent units, the coordinate solution is no longer limited to one clock synchronization unit, which also leads to an increase in the uncertainty of the number of measured values and the layout of base stations involved in the position calculation. Taylor algorithm cannot meet the solution requirements, so the improved salphus swarm algorithm is used instead of Taylor algorithm to calculate the cooperative positioning position, and finally the position coordinates of the point to be measured are obtained. The experimental results of the cooperative positioning of adjacent units of six base stations show that the R95 value of each measuring point is between 12 cm and 15 cm, and the maximum residual error is between 16 cm and 23 cm. The method proposed in this paper does not need multi-parameter judgment to choose or reject position information, which effectively solves the problem of multi-solution of position and improves the positioning accuracy.