It is raining when i got home last night ?

The sentence you provided is in the past tense, indicating that it is referring to an event that occurred in the past. If you are asking whether the sentence is grammatically correct, it is missing a subject and a verb. A corrected version of the sentence could be:

“I arrived home last night while it was raining.”

In this corrected sentence, “I” is the subject, “arrived” is the verb, and “while it was raining” is a subordinate clause that describes the weather conditions at the time of the arrival.