The invention discloses a direct positioning method based on time difference and frequency difference. In view of a passive dual-satellite time difference and frequency difference positioning problem, the invention discloses a positioning method of firstly determining a target position range based on TDOA (Time Difference Of Arrival) and then based on a FDOA (Frequency Difference Of Arrival) model, the FDOA does not need to be measured, the difficulty of solving the time difference and the frequency difference is avoided, and the positioning precision is higher than that in a method of firstly measuring the FDOA and then performing positioning. Compared with the method of firstly measuring the time difference and the frequency difference and then performing positioning, the method of the invention has the advantages of simple processing and high positioning precision, and particularly in a condition of a low signal to noise ratio, the positioning precision has large advantages. The method does not need to change hardware design of the positioning system only needs to adopt a new positioning algorithm and is applied to engineering application and promotion. The dual-satellite time difference and frequency difference positioning precision can be improved, and a certain reference value is provided for positioning of other platforms and other positioning mechanisms.