Strawberry jam grows tremella in the fresh-keeping cabinet. Can I eat?

When you say "tremella", it's actually mold, in other words, it's moldy. If it is moldy, it is not recommended to eat it again. Mold may produce toxins. Even if you don't eat the mold visible to the naked eye directly, the mycelium and spores of the mold may have dispersed long ago. Eating such food may lead to food poisoning due to toxins.