When i rotate an object by 360 degrees in 100 frames and playback the animation, the object rotates fast in the first 10-20 frames,then slowly,then again fast in the last 10-20 frames.
(In doing this i made a key on frame 1 at 0 degrees and on frame 100 at 360 degrees)I also playblasted it,but same thing happened.

How can i get uniform rotation speed throughout the animation(100 frames)?

I did that but still the same thing is happening.
I have attatched my file (500 frames) ; with this message.
In this file i have breaked the tangents as you said but still their is no uniform speed.
Please see it and tell me what is wrong.
Thanks in advance…

Your file did not attach…
Can you post a screenshot of your graph editor with the object selected?

n8skow [FA]

how can i attatch a file in my post?
(i click on browse, give the path of my file and post the message, but file is not attatched.)

There is a max file size of 3500KB allowed in attachments.
Also, you can’t attach a .ma/.mb file directly - you’ll need to .zip or .rar it to post.

n8skow [FA]

Playing back your animation in Maya is unreliable - it depends on your timeline settings, your RAM, your cache, the complexity of your scene - lots of things.

Did you do a playblast of the scene, or a render? 

From the sound of your question, it seems like you’re just hitting “play”, but your animation is probably OK.

oops - must read more carefully.  Didn’t see that you had playblasted it.