I think Napoleon is worse than Snowball.
--语法上没错.
Snowball though like apple and milk.He is passion to help every animal yet.
--though和although必须放在句首,不过在口语中,though可以放在句尾.like时态错误,现在时的话应该加s,不过根据文意,过去时可能更加妥当.yet放着没有意义.passion是名词,在is后面不妥,应该用passionate.稍作调整后,改为：Although Snowball liked apple and milk,he is still willing to help the animals.
But Napoleon insulted Snowball by telling him that he was timid.And said that Snowball overthrown the windmill,made trouble in the night.
--but必须引导从句,它引导的句子在书面语里不可单独成句.and在书面语里也不可单独引导句子.overthrown是过去分词,应在has/had之后.我不清楚你要表达的意思是什么,但是靠我猜想的意思作了些调整,改后句子为：However,Napoleon insulted Snowbal by accusing him a timid person,and by saying that the windmill he overthrew had caused troubles in the night.
Napoleon broke Seven Commandments.
--Napoleon had broken the Seven Commandments.理由不用说了吧.
He changed some words to conceal his crime.
--语法是对的.但是不知道你是什么意思.
He killed some innocent animals on the pretext of they are Snowball’s spy.
--on the pretext of后面应该是跟名词,而不是从句.spy应该为：spies
我试改为：He killed some innocent animals by misaccusing them of being Snallball's spies.
Real men make an honest living.
--语法没错,意思很别扭.
Napoleon is selfish and doctorial.
--语法没错,doctorial很别扭.
He deprived animals equal and foods.
--equal用词不当.animals后面加of.
He is crazy and evil.
--ok
He put a long scheme to dominate the farm like Jones.
--语法没错,意思很别扭.
Also has this may be worse than.
--没有主语,than后面应该有个名词/动名词.
把中文贴一下,这样我可以做更多改动.