The heat pump with low global warming potential (GWP) refrigerants is imperative for the electric vehicle (EV) to slow down global warming and extend the driving range while meeting passengers' thermal comfort in low ambient temperatures. However, there are no appropriate refrigerants. To provide long-term and environmental-friendly refrigerants in the heat pump for EVs, herein, we reported newly developed low-GWP refrigerant mixtures, i.e., DL3B, whose GWP is lower than 140, the flammability (lower flammability limit and burning velocity), saturation pressure, lubricant miscibility, material compatibility were experimentally tested. A test bench that can investigate the performance of an R410A prototype was built. The drop-in tests of the DL refrigerant were carried out to evaluate the capacities and COPs for both cooling and heating modes in the EV heat pump system. Results showed that DL3B has similar saturation pressure to R410A, good miscibility with original lubricant and is compatible with both metallic and non-metallic materials. 6.The heating capacities of DL3B were 101.8-112.8% of the R410A system, with COP being 84-99.8%, while the cooling capacities showed 118.9-128.4% of the R410A system, with COP being 98.2-108%. DL3B showed very weak flammability and can be classified as A2L according to the ASHRAE standard. Besides, our real car road test showed very good heating performance even in -25 °C ambient temperature with similar warm-up performance to R410A. Our results certificated the promising potential application of the DL refrigerant in EV heat pumps.