System Idle Process with its checksum, it has its own identity, it is needed to regulate Operating System and it is safe.

But in case of System Idle Process Virus, it can infect and dangerous/ malicious.

System Idle Process is what your computer does while your computer is idle. It does nothing for you or against you. And no, there's no way to use it other than making your computer go idle.

don't know why my CPU usage is totally consuming by program called SYSTEM IDLE PROCESS

When the System Idle Process is running at a high percentage, it means that your computer isn't doing anything that requires much use of the CPU at that time. For example, if you are using 5% of your CPU, the System Idle Process will be using 95% of the CPU, which means that 95% of the CPU is not being used.

The system idle process does not actually use any CPU time. It just merely calculates what percentage of the CPU is being used by your processes at any given time.