Inaccurate receiver position information directly influences the timing results for users. The impact of receiver position error on timing is studied in the terms of both theory and experiment. Theoretically, the biggest impact on receiver position error is obtained by differentiating the pseudorange equation in the first order. To avoid the influence of satellite position error, the precise satellite positions provided by IGS are used to correct the theoretical results. In experiments, the impact of position error on timing result is also studied by analyzing GPS/GLONASS receiver observation data under the errors in different directions and orders of magnitude. The different situations in the practical scenarios are also analyzed. Experimental results show that the timing accuracy of GPS and GLONASS is less than 5and 15 ns by every increase of 1 arc second latitude error, and timing stability is less than 10 and 15 ns respectively. The timing accuracy of GPS and GLONASS is less than 1 ns for each additional arc second error of longitude, and both less than 10 ns of timing stability. Every increase one meter of elevation error can cause about 3 ns timing error and the influence on timing stability is about 0.3 ns/m. In the practical applications, users can refer to this conclusion for considering input coordinates of timing receivers according to the demand of timing precision.