Aiming at the problem of delayed spray in automatic target spraying, a real-time control target spray system was designed. The system took the laser detection and ranging (LiDAR) as the detector and the real-time speed of the spray vehicle was obtained by using the true ground speed sensor (TGSS), and a delayed spray model was established, which continuously adjusted the spray delay time. The delay spray model included delay memory and delay counter. The delay memory used the FIFO buffer to store the spray instruction temporarily. The delay counter was pointed to the delay memory address, which used the current vehicle speed to calculate the delay index. The delay counter took out the spray instruction corresponding to the delay memory address and sent it to the solenoid valve controller to realize the target spray. The response time of the system was firstly analyzed in the experimental part, including identifying target time, calculating the spray command time, communication time and the response time of the solenoid valve. The experimental results showed that the system response time was 160ms and the delay memory had 42 delay units. Secondly, the accuracy of the MCU in calculating the frequency of the TGSS signal was compared by using the M method and T method with the Proteus simulation. Experimental results showed that the M method was more suitable for the frequency calculation of the described speed measurement system. Then, the speed of the spray vehicle was proportional to the frequency of the square wave signal after the installation angle of TGSS was determined. The proportional coefficient was determined to be 0.0099 through fitting. The r-squared of linear fitting of speed and frequency was 0.9998. Finally, the experiment verified the overall effectiveness of the real-time control to the target spray system and measured the minimum recognizable spacing of the real-time control to the target spray system. The experimental results showed that the minimum recognizable spacing was between 80mm and 180mm, the ability of the system to recognize the target spacing was decreased with the increase of the speed of the spray vehicle, when the target spacing was greater than 180mm, the system can identify targets effectively.