The work aims to develop a composite film that can maintain good mechanical properties at low temperature, and provide a reference for solving the problem that the plastic packaging of prefabricated vegetables and other products is prone to embrittlement at low temperature, resulting in easy breakage during transportation. The film was prepared by blending polyamide 6 (PA6) with low density polyethylene (LDPE) in a certain proportion. With maleic anhydride grafted polyethylene (PE-g-MAH) and maleic anhydride grafted polyolefin elastomer (POE-g-MAH) as compatibents, the effects of different additive amounts of compatibents on the properties of the composite film were investigated. Then, the film was characterized through the light transmission properties, mechanical properties, water contact angle, water absorption properties, barrier properties, Fourier infrared spectroscopy, Search Engine Marketing (SEM) and Differential Scanning Calorimetry Differential Scanning Calorimetry (DSC). The addition of compatibilizers could improve the performance of PA6/LDPE blend system and 5% PE-g-MAH and 10% POE-g-MAH could improve the comprehensive performance of the composite film. The addition of these two compatibilizers could improve the poor compatibility between PA6 and LDPE, and enhance the combination firmness of continuous phase and dispersed phase. The tensile strength of the composite film at −40 ℃ was 41.57% and 40.13% higher than that of the PA6 film, and the elongation at break increased by 40.5% and 60.13%, respectively. At the same time, the addition of compatibilizer improved the water absorption of PA6, and the water absorption, water vapor permeability and hydrophobicity of the composite film were improved. Adding 5% PE-g-MAH or 10% POE-g-MAH into PA6/LDPE composite film has the greatest improvement on the overall performance of PA6/LDPE composite film. PA6/LDPE/PE-g-MAH 5% and PA6/LDPE/POE-g-MAH 10% composite films can still maintain good rigidity and toughness at low temperature, while improving their water absorption and water vapor barrier properties.