Disclosed are a diaphragm for a sound generating device and a sound generating device. The diaphragm comprising at least one elastomer layer, wherein the elastomer layer is made of an ethylene propylene diene monomer; and the ethylene propylene diene monomer is formed by polymerizing three monomers, the three monomers being an ethylene monomer, a propylene monomer and a non-conjugated diene monomer respectively, a mass ratio of the ethylene monomer to the propylene monomer ranging from 0.25 to 4, and content of the non-conjugated diene monomer being 1%-15% of total content of the ethylene monomer and the propylene monomer. The ethylene propylene diene monomer has excellent high-temperature resistance and thermo-oxidative aging resistance; and after the rubber is made into the diaphragm, the diaphragm is capable of working in a high-temperature environment for a long time, maintaining not only excellent elasticity but also excellent anti-fatigue characteristic, thereby possessing excellent reliability.