Can i apply locoid cream 0,1% hydrocortison. butyr. on my vagina?

Ask your OBGYN first, don't try to self medicate yourself. Unknown side effects could be harmful.

Only if so prescribed by your doc, use for vaginitis is off label and unless you have a clear understanding of your condition, clear instructions, duration of treatment, etc from your doc would recommend against its use, it can definitely worsen undiagnosed or misdiagnosed conditions.