In order to accomplish the power supply for aircraft flight parameters real-time measurement system, an autonomous power supply system, which composed of flexible solar film, ultra-thin lithium battery and voltage change with charge-discharge management circuit, is studied. The system performance test is also completed. The test results show that the autonomous power supply system can charge 1 800 mAh ultra-thin lithium battery from no power to full power within 296 minutes, when the light is sufficient. And it would take 386 minutes when light get weaker. When the ultra-thin lithium battery supplied power to the flexible composite sensing and measuring module alone, it could work at full load for about 625 min. When the power supply came from flexible solar film and ultra-thin lithium battery, the lithium battery voltage decreased from 4.15 V to 3.51 V, after two sunny days and two cloudy days, and the flexible composite sensing and measuring module worked at full load for 1 678 min. It is concluded that the autonomous power supply system meets the demands of long-term stable power supply for flight parameters measurement system.