When washing machine is in rinse mode it slowly starts to fill my kitchen sink.what can I do ?before calling a plumber.

Howdy-

We need more information--

Is your washing machine emptying into the sink-- washing machine hose hooked over edge of sink?

Or does washing machine empty into it's own dedicated drain?
If washing machine has its own dedicated drain, is this drain in line with sink drain?

Is this a clothes washer or a dishwasher? A clothes washer requires a 2" drain.