The grout sleeve has been widely used in prefabricated concrete structures as an important rebar connection technology. However, grout defects may occur due to manual miss operation or poor control approaches for quality, and the existing research on grout defects detection methods and accuracy are still insufficient, which seriously affects the construction quality and structural safety of prefabricated concrete structures. Therefore, there is an urgent need for a detection method that can detect the overall defects of specimen without damaging specimen and has higher detection accuracy. Based on this, a non-destructive resistance detection technology based on the conductivity of the slurry was proposed. Firstly, the basic principles of this detection technology were introduced, and a slurry fullness detection equipment was provided. Practice showed that using this equipment did not cause damage to the sleeve during the detection process, and the defective sleeve could be quickly repaired after detection, the defective sleeve strength was further improved. So this equipment can be promoted. In addition, analysis and resistance theoretical calculation were performed for insulating sleeves and non-insulating sleeves. The results showed that it is feasible to use the non-destructive resistance method to detect the resistance of grouting materials. However, when applying the non-destructive resistance method for detection, the rebars and sleeves must be insulated before construction to effectively avoid the error and interference of current in order to improve the accuracy of the test results.