Abstract: The crystallization temperature of plagioclase in the andesite (H5-T3-2) in the southern Mariana Trough is mainly concentrated in 1 050～1 150 ℃, which is not affected by the later magmatic evolution. The crystallization temperature of plagioclase in the basaltic andesite (H5-T1-3) in the central Mariana Trough is mainly concentrated at 900～1 050 ℃. The crystallization temperature of plagioclase in dacite (H5-T1-1) is mainly concentrated in 1 050～1 150 ℃. The uniform temperature of the melt inclusions in the basalt (H5-T2-2, H5-T2-3) plagioclase near 18°N in the Mariana Trough is mainly concentrated at 1 050～1 150 ℃, and shows a continuous cooling trend, only a small part crystallizes at a lower temperature of 1 000～1 050 ℃, and the sudden drop of An at the edge reflects the rapid cooling stage of the magma ejection process. The uniform temperature of the melt inclusions in basalt andesite (H5-T2-1) plagioclase has the characteristics of "bimodal", and the uniform temperature is mainly distributed in the two temperature ranges of 850～950 ℃ and 1 050～1 150 ℃. Combined with the ring characteristics of plagioclase and its An value change characteristics, it is shown that the plagioclase has two distinct crystallization stages, magma mixing occurs, and there may be a magma chamber in the shallow part of the Mariana Trough, and the magma chamber temperature is about 850～950 ℃. The magmatic evolution process near 18°N in the Mariana Trough is complex, and different periods of magmatic evolution occur.