Abstract: Objectives: Global Navigation Satellite System (GNSS) heading determination is an important technology in the field of navigation. At present, the accuracy of high-performance GNSS heading determination receivers can reach 0.20(°)/m, which can satisfy the requirements of most applications, but the cost of 10, 000 yuan hinders the mass market promotion. However, the observation redundancy and quality of the low-cost GNSS receivers are weaker than those of the high-performance GNSS receiver, which makes the heading determination accuracy and reliability of the low-cost GNSS receiver vulnerable to complex environments. Methods: In order to improve the performance of low-cost GNSS heading determination, a low-cost GNSS heading determination method with fixed baseline constraints is proposed in this paper. The method deploys fixed baseline constraints between the dual antennas and constructs real-time dynamic detection thresholds based on a posteriori variance-covariance of geometric baseline, which can effectively increase the success rate of integer ambiguity resolution, thus improving the accuracy and reliability of low-cost GNSS heading determination. Results: The proposed method was tested with real kinematic data. Compared to the traditional methods, the success rate of the integer ambiguity resolution was improved by 7%, and the heading determination accuracy of 0.4 (°)/m was achieved. Conclusions: It is shown that the low-cost GNSS vectoring method with fixed baseline constraints proposed in this paper can effectively increase the success rate of whole-period ambiguity solution and improve the accuracy and reliability of low-cost GNSS vectoring.