BACKGROUND: Evidence is limited regarding the association between temperatures and health costs. OBJECTIVES: We tried to investigate the association between temperatures and emergency department visits (EDVs) costs in China. METHODS: Daily data on EDVs costs, weather, air pollution were collected from 17 sites in China during 2014-2018. A quasi-Poisson generalized additive regression with distributed lag nonlinear model was applied to assess the temperature-EDVs cost association. Random-effect meta-analysis was used to pool the estimates from each site. Attributable fractions and national attributable EDVs costs due to heat and cold were calculated. RESULTS: Relative risk (RR) due to extreme heat over 0-7 lag days was 1.14 [95% confidence intervals (CI): 1.08-1.19] and 1.11 (95% CI: 1.07-1.16) for EDVs examination (including treatment) and medicine cost, respectively. People aged 18-44 and those with genitourinary diseases were at higher risk from heat. 0.72% of examination cost and 0.57% of medicine cost were attributed to extreme heat, costing 274 million Chinese Yuan annually. Moderate heat had lower RR but higher attributable fraction of EDVs costs. Exposure to extreme cold over 0-21 lag days increased the risk of medicine cost for people aged 18-44 [RR: 1.30 (95% CI: 1.10-1.55)] and those with respiratory diseases [RR: 1.56 (95% CI: 1.14-2.14)], but had non-statistically significant attributable fraction of the total EDVs cost. CONCLUSIONS: Exposure to heat and cold resulted in remarkable health costs. More resources and preparedness are needed to tackle such a challenge as our climate is rapidly changing.