why ARM supported keil Version is not supporting to 8051 keil version
ARM and 8051 are two entirely different architectures - so you you'd always need 2 differents toolchains.
Even GCC - which supports many different architectures - doesn't include 8051!
But you can have both 8051 and ARM tools installed on the same PC, and they will then use exactly the same uVision interface - so what exactly do you want?
"why ARM supported keil Version is not supporting to 8051 keil version"
Sorry, what ???