In order to compare the mechanical performance differences between grouted sleeve lapping connectors and butt connectors, uniaxial tensile and high stress repeated tension-compression tests were conducted on 41 lap connectors and 20 butt connectors. Results showed that under uniaxial tension and high stress repeated tension-compression loading, the total elongation ratio with maximum force of two kinds of connectors was greater than 6% and the ductility coefficient was greater than 4. The strength basically met the requirements of the codes. Under uniaxial tension after high stress repeated tension-compression, the bearing capacity of both connectors increased, while the initial stiffness and ductility of the specimens decreased. Moreover, the residual deformation of the lap connector was reduced by the anti-deflection measures, but the measured value of the residual deformation of the lap connector was slightly larger than that of the butt connector due to the limited constraint stiffness of the anti-deflection measures. However, the residual deformation of the lap connector and the butt connector of anti-deflection generally met the requirements of the specification. After high stress repeated tension-compression, during uniaxial tension testing, the middle section of the sleeve of the lap connector was longitudinally compressed and circumferentially stretched in the early stage of loading. In the later stage of loading, it experienced longitudinal stretch and circumferential compression, while the sleeve of the butt connector was longitudinally stretched and circumferentially stretched throughout the loading process. In the case of uniaxial tension after high stress repeated tension-compression, the maximum longitudinal tensile strain of the middle section of the sleeve near the bar side of the anti-deflection and non-deflection lap connector was 0.10 to 0.39 times and 0.13 to 0.18 times of the butt connector, respectively. Furthermore, the maximum circumferential compressive strain was 0.09 to 0.49 times and 0.02 to 0.32 times of the butt connector, respectively, which indicated that the lap connector had relatively low requirements on the material of the sleeve. When the diameter of rebar was the same, the material cost of the lap connector was about 35% lower than that of the butt connector.