【Objective】 Camellia reticulata is the first of the eight famous flowers with evergreen leaves and bright colors, but its cold tolerance is poor. This paper discusses the cold tolerance of two ploidy Camellia reticulata from the physiological and molecular levels, which can provide references for the mining of cold tolerance genes and molecular breeding of Camellia reticulata. 【Methods】 Using tetraploid (4X) and hexaploid (6X) annual seedlings of wild Camellia reticulata as experimental materials, physiological indexes and transcriptome sequencing of leaves of Camellia reticulata. were determined after low temperature (-4℃) stress treatment (0 h, 24 h, 72 h, reheated for 48 h and reheated for 72 h). 【Results】 From the observation of leaf phenotype, from the stress period to the rewarming period, the damage degree of hexaploid leaves was relatively small, and the cold resistance performance of hexaploid leaves was better than that of tetraploid leaves. According to the results of physiological indexes, except