If you visit any admin/franchise/clients sites, these sites always have logo on the left top corner. What is the golden rule for admin site logo height? as i have build a logo with 50px height but its looking quite tall, because there is some old printed images which increase the height of logo and i can not change these images height. i need your suggestion about admin site header and logo.
There is no golden rule. Marketing wants it twice as large. The UI designer wants it twice as small. So just go somewhere in between.
Hard to visualize the problem you have. Not sure there's a golden rule to logo height - but 40 to 70px sounds about right, probably including padding, but it depends on the rest of the content and whether it's wasting space right along the top. Look at this very page for example.
[Edit] Added some examples below. If you are forced to have a 15px padding top and bottom, then a 30px logo looks too small, between 40 and 50 looks better. Depends on your colour scheme, aspect ratio of the logo, and what else you have in the same horizontal panel as the logo...?
50px does not seem unreasonable at all. Any size that is at least legible but not obtrusive should work.