The invention provides a diaphragm for a microspeaker and a manufacturing method thereof. The diaphragm is a single-layer diaphragm or a multi-layer diaphragm and comprises at least one layer of a chemically cross-linked thermoplastic polyester elastomer, wherein: the chemically cross-linked thermoplastic polyester elastomer has a loss factor less than or equal to 0.4 at a temperature range not higher than a softening temperature of thermoplastic polyester elastomer before chemical crosslinking plus 40° C., as measured by a rheological curve; and the diaphragm further has a yield strain in the range of 7% to 30%. The diaphragm for a microspeaker according to the technical solution of the present invention is easy to be prepared by thermoforming, and has appropriate modulus, good strength, elasticity, and thermal stability.