I can't find the key to open the bandit's gate, can anyone tell me wher…

One is in the pool on the way to the trading post and the other can't be reached until you complete a few side tasks. It's in the pool that can only be accessed by walking down the river to get to it. You'll have to demolish and reconstruct your bridges to get there. For some reason, your hero can't walk there right away. I had to finish the bakery and the Tornado alley side-adventures and then I was allowed to walk down the river.

Hope that helps!

Thanks, got it :)

thanks for tip but i tried to get there i got to the gate but now i cant get away i passed tornado valey and bakery but nothing done it please help me how can i find the key

I don't quite understand you. What do you mean you can't get away? Away from what?
You need to walk into the river to get to that one pool near the bottom of the map. Have you tried walking there yet?