How to test bitcoin distribution mechanism Now I'm developing a bitcoin distribution mechanism (according to users' submitted shares count). The complete workflow is: Users submitted shares to my pool, then my pool submitted these shares to another famous pool (e.g. btcguild). When my pool received bitcoins from the remote pool, it will distribute these received coins to users (according to their submitted shares count)

The problem is that everytime I test this mechanism, I will create many transactions, but each transaction will take 0.005 btc as transaction fee for bitcoin network. Then after paying 200  users, I will pay 1 btc to bitcoin network, The cost is high. Is there any way to simulate the bitcoin network, so I can create transaction without paying transaction fee?
As Nate Eldredge suggest, you could use the Bitcoin Testnet. This is a separate Bitcoin fork that exists especially for testing purposes.
You can easily get some testnet coins from testnet faucets.

Besides that, do you know that it is possible to create a transaction with multiple inputs and multiple outputs? So instead of creating many transactions, you could combine them into one transaction and only pay the fee once.