The main technologies used in ultrawideband(UWB) based positioning systems are TOA and TDOA. However, the low positioning speed of TOA algorithm and the unstable positioning accuracy of TDOA algorithm limit the development of UWB positioning system. In order to balance the shortcomings of the two algorithms in positioning speed and accuracy, this paper proposes a new TOF and TDOA joint positioning algorithm combination of TDOA and TOF(CTT). The algorithm only needs three times of UWB communication to measure all time difference information and a TOF distance value required by the TDOA algorithm, and can calculate the distance between all base stations and a single tag in the positioning area. The positioning speed of CTT is at least 50% higher than the TOA algorithm. DW1000 is used to compare the positioning accuracy of TOA, TDOA and CTT algorithms respectively, the results show that the average positioning error of CTT algorithm in twodimensional case is less than 20 cm and the standard deviation is less than 10 cm, close to the accuracy of TOA and solve the instability of TDOA algorithm.