针对BDS中长基线RTK定位中整周模糊度受大气延迟误差影响难以正确固定的问题，提出一种BDS中长基线三频整周模糊度确定方法。采用MW组合确定B2-B3超宽巷整周模糊度，利用B2-B3超宽巷和B1-B3宽巷组合观测值所受电离层延迟误差较接近的特点，确定B1-B3宽巷整周模糊度。利用无电离层组合解算窄巷整周模糊度和相对天顶对流层延迟误差，最终实现实时动态定位。利用实测的BDS中长基线进行算法验证，结果表明，该方法可有效固定中长基线三频载波相位整周模糊度，获得cm级定位精度。

As integer ambiguity is affected by atmospheric delay error, it is difficult to correctly fix ambiguity between BDS middle-range baseline. We propose the algorithm of triple-frequency ambiguity resolution between BDS middle-range baseline. We use the combination of MW to determine B2-B3 extra-wide-lane integer ambiguity, and then solve the B1-B3 wide-lane integer ambiguity using the closer characteristic of ionospheric delay error between B2-B3 extra-wide-lane and B1-B3 wide-lane combination observation. We use the ionosphere-free combination observation to estimate narrow-lane integer ambiguity and relative zenith tropospheric delay error, and finally the real-time dynamic positioning is realized. We test this algorithm by the measured BDS middle-range baseline. The results indicate that the method can fix the triple-frequency carrier phase ambiguity between middle-range baseline correctly and effectively, and positioning accuracy to the centimetre level can be achieved.