True color composite image using multi-spectral remote sensing data is fast in processing speed, independent of other remote sensing products, and easy to interpret. It plays an irreplaceable role in fields such as meteorology, ecological environment, and disaster reduction. In this study, the data from Medium Resolution Spectrum Imager-Ⅱ (MERSI-Ⅱ) onboard Fengyun-3D (FY-3D) are utilized to composite true color image after atmospheric correction and nonlinear stretch. True color image can detect disasters such as sand and dust, blue-green algae, fire, and typhoon. Relevant results indicate that true color image can identify the affected area, development and changes, and some other useful information in the above-mentioned events.