In order to solve the problem of the quality of the reflector layout in the laser guided AGV (automatic guided vehicle) system,a method to measure the distribution quality of reflector plate by calculating horizontal dilution of precision(HDOP) is proposed in this paper.HDOP reflects the relationship between the geometric layout of the landmarks and the positioning accuracy in the positioning system.Under the same ranging accuracy,the smaller the HDOP value of the undetermined position,the higher the positioning accuracy of that position.Through the positioning simulation experiment,the relationship between HDOP value and positioning error under four positioning schemes is analyzed.The results show that the position where HDOP is smaller,the positioning accuracy of AGV is higher.When the test point is located in the closed area enclosed by the reflection plate and the number of reflector is reasonably increased,the HDOP value of the test point as well as the positioning error is small.Based on the result,the positioning accuracy of AGV can be improved by setting the position of reflectors reasonably and increasing the number of reflectors.