The evaluation of grouting defects in precast beam grouting sleeves has long been a focal point of scholarly research, with the impact of horizontal defects on performance surpassing that of end and vertical defects. Aiming at the problem of horizontal grouting defect evaluation, the active excitation signal of AST (auto sensor test) and PLB (pencil-lead breakage) function built in acoustic emission instrument was studied, combined with horizontal sleeve grouting fullness test. Through parameter analysis and fast Fourier transform, changes in acoustic emission wave velocity, energy, count and waveform parameters are examined at filling degrees of 50%, 60%, 70%, 80%, 90% and 100%. Furthermore, the correlation between acoustic emission energy, count parameters and main frequency amplitude with grouting fullness was established. The results show that when the excitation source is AST, the acoustic emission energy, count and the main frequency amplitude of its waveform show a good negative exponential correlation with the increase of grouting sleeve fullness, and the combination of the relational equations allows for quantitative acoustic emission analysis and evaluation of grouting fullness of horizontal grouting sleeves.