GNSS can be used to obtain the attitude information of dynamic carrier. In order to improve its attitude measurement accuracy, this study proposes a weighted least squares attitude solution method based on baseline length information, which improves the least squares attitude solution method. At the same time, the availability of this method is verified by shipboard experiment. The experimental results show that in the ship borne dynamic experiment, when there is an obvious difference in the baseline length, the accuracy of the weighted least square method is significantly higher than that of the equal weight least square method, and the accuracy of roll angle is increased by 13 %.