This paper studies the impact of carbon trading policies on breakthrough low-carbon technological innovation through a difference-in-differences model based on the panel data of 30 provinces in China. Through descriptive statistics, regression analysis, a robustness test and heterogeneity analysis of the data, the results show that: (1) carbon trading policy has a significant effect on overall low-carbon technological innovation and gradual low-carbon technological innovation, and carbon trading policy lag can significantly promote breakthrough low-carbon technological innovation. (2) The timeliness of carbon trading policy in promoting breakthrough low-carbon technological innovation is different in different regions. The effect can quickly be displayed in some provinces, but there is a lag effect in other provinces. (3) Lags in carbon trading policy have promoted a significant increase in renewable energy technology patents and CCS-related technology patents, and contributed more to the increase in renewable energy technology patents.