Abstract: The aerosol particle hygroscopic growth factor (GF), aerosol liquid water content (ALWC), particle number size distribution (PNSD), and particle chemical composition in Chengdu from January to February 2019 were observed by using a Hygroscopic Tandem Differential Mobility Analyzer (H-TDMA) and an aerosol component monitor (S-611EG). Combined with meteorological factors, the hygroscopic effect of atmospheric aerosols in Chengdu and its impact on visibility were analyzed. The results showed that: (1) The hygroscopic growth factor of non-hygroscopic mode particles (GF_NH) in the size range of 40–200 nm in Chengdu in winter decreased with increasing particle size, while the hygroscopic growth factors of both strong and weak hygroscopic mode particles (GF_{MH, LH}) increased with increasing particle size, and the proportions of non-hygroscopic and weakly hygroscopic particles (NF_{NH, LH}) decreased with increasing particle size. (2) The aerosol liquid water content in Chengdu in winter was dominated by particles in the Aitken mode and accumulation mode, with the Aitken mode contributing the most to ALWC. The influence of relative humidity (RH) and fine particulate matter (PM_2.5) on ALWC decreased in that order, and high PM_2.5 combined with high RH was a sufficient condition for high ALWC. (3) Adverse meteorological conditions were the main cause of the haze event in Chengdu. Low visibility resulted from the accumulation of PM_2.5 under low RH conditions, while the hygroscopic growth effect of aerosols dominated the visibility reduction under high RH conditions.