He found his hometown greatly changed 怎么樣改為主從句形式？

He found his hometown greatly changed. 過去分詞作賓補為被動意義。

假如要表示主動意義，則不可以用changed過去分詞作賓補，而應該用that從句：

He found that his hometown had greatly changed. 主動意義。

所以，你的句子假如改為that從句，要用被動語態。

He found that his hometown had been greatly changed.