A novel shear connection system for GFRP box-concrete composite girder was proposed and experimentally and analytically investigated in this paper. The novel connection system consists of T-bolts and sand coating, and can be easily installed at the GFRP box section with closed shape. The proposed connection system can improve the slip stiffness of GFRP box-concrete interface, and provide sufficient shear resistance and ductility. The effects of low temperatures (T = 20, −30, −60, and −80 ℃), longitudinal spacing of T-bolts (SL=100, 150, and 200 mm), aspect ratio (hef/d=3.2, 5.2, and 7.2), and GRRP-concrete interface type (IT=combined connectors with T-bolts and sand coating, sand coating, T-bolts, and blind-bolts) on interfacial shear behaviours were evaluated through twenty-four push-out tests. Failure modes and load-slip/strain curves at different temperatures were plotted. Experimental results showed that decreasing temperature from 20 to − 80 ℃ increased the shear resistance of sand coating and slip stiffness of push-out testing specimens, but exhibited little effects on their ultimate shear resistances. Analytical equations to predict the ultimate shear resistances of push-out testing specimens have been developed and validated by the test results. Besides, load-slip modes for specimens with different interface types were also proposed with good accuracy. •Combined connectors with T-bolt and sand coating are proposed for composite girder.•Combined connectors improve the slip stiffness, shear resistance and ductility.•Low temperature increases the interfacial shear resistance and slip stiffness.•Analytical models predict well the ultimate shear resistance and load-slip curves.