The peak-load during summer has always been a critical period for power supply，new energy as the main component of the future new power system，also facing the “great test” of safety supply. Owing to the uncertainty and volatility of wind and light power generation，the actual support capacity of new energy cannot effectively meet the needs of large load growth，real-time system balance and continuous operation in the summer when the high temperature electricity load continues to rise，and the power system with a high proportion of new energy is facing greater challenges in terms of its ability to maintain supply. This paper relies on big data means to analyze the five-year sample data of wind and light power generation output in Henan Province since 2018，to measure the effective supply capacity of new energy，to assess the power balance support capacity of new energy during the summer supply，and to explore countermeasure suggestions to improve power supply and increase supply by multiple measures in view of the low credible power output rate of new energy during the critical time of summer supply.