When my washing machine is draining then it's starts backing in bath tub so I don't know what to do ?whether my cess prblem or washer drain blocked? Or my washer drain should be taken separately in out side of house ?or prepare a new drywell for this? Please give me answer.Thanks

Cess pool or septic tank? If it has worked for years and now it does not then you have aclog down stream of where the two drains come together. You can rod the line by rodding down the washer stand pipe or through the tub over flow plate

Locate the house cleanout and open it up.
Now cycle the washer. If the clean out overflows then the cesspool/septic tank needs pumping. If the tub backs up then follow Bobs advice. One more place you could snake would be the lavatory roof vent, Good luck, Tom