GNSS time transfer technology is an important application of satellite navigation technology in time and frequency domain, and is also one of the main means of time transfer. With the continuous development of China′s Beidou satellite navigation system, the applications in the fields of time and frequency based on Beidou also gradually increase. In his work, time transfer algorithm is focused and software package (PPTSlo) is developed using Beidou common view and carrier phase technology, based on specific IGSO, MEO, GEO satellite constellation in Beidou satellite navigation system. The time transfer link accuracy and stability is analyzed by qualitative and quantitative analysis. Experimental results show that Beidou common view time transfer accuracy is better than 6ns, Beidou carrier phase time transfer accuracy can reach subnanosecond to nanosecond.