For quantitatively researching the response of Laohugou basin's runoff to climate change, using meteorological and runoff data of Laohugou basin in the strong ablation period of 1959 and 2014, the changes of air temperature, precipitation, evaporation, glacial ablation, runoff in the strong ablation month (July) of 1959 and 2014 in the whole basin were analyzed. The melting process and runoff response to climate change in the Laohugou basin also discussed. The results showed that in July, 2014, the climate change led to runoff increase 159 mm, accounting for 49.67%,higher than that in 1959; the monthly mean air temperature in July had increased 0.38 ℃,and the monthly minimum temperature had increased 1.34 ℃ as compared with that in July, 1959. Precipitation was the same nearly in July, 1959 and July, 2014. There was a negative correlation between precipitation and runoff; there was small change in evaporation; the ratio of mixed state precipitation had decreased by 23.01 %,resulting in increasing the proportion of precipitation translating directly into runoff. The cumulative positive temperature had played a decisive role. The cumulative positive temperature in July, 2014 was 11.71 ℃ · d higher than that in July, 1959, mainly due to the temperature of 2 - 4 ℃ increasing, resulting in cumulative positive temperature increasing,which intensified the supply of meltwater to runoff.