Yes you can override the start method of the thread class.

if you extend from the thread class. and override.
then only start method will be called

we can override  start() method present in Thread class.but
we have to follow following steps:

1) first our class must extend thread class.
2)then we have to override thread class start() in such way
that :
a) It should instantiate and register our new thread with 
thread scheduler.
b)  it should call run() method.(it may be our overridden
run method or thread class run() method)

Subhareddy, can u please send me one example on above
question??

We can override start() method but it is not recommended. 
Why because...the start() method of Thread class first 
registers a new thread with the Thread Scheduler and it 
invokes run() method.