Abstract: Due to the complex internal structure of steel bar sleeves, there is still a lack of simple and effective detection and identification technology for the grouting construction quality of steel bar sleeves in prefabricated buildings. Although the structural defect detection technology based on the vibration method has a simple and convenient detection process, due to the complex internal structure of steel bar sleeves, it is difficult to detect the grouting defects in the sleeve in the time-frequency domain. Through vibration test experiments, this paper explores the relationship between the fractal box dimension value of the sleeve vibration response signal and the sleeve grouting defect. The test results show that different excitation and vibration test positions will significantly affect the size of the vibration response signal box dimension of the same sleeve. By using the method of exciting at the sleeve grout outlet and testing at the grout inlet, it is possible to preliminarily judge whether the grouting in the sleeve is full according to the size of the box dimension. However, for more refined detection of grouting defect sizes, further research and exploration are still needed.