[johnxu]

My kitchin sink drain has been blocked. Water drains very slowly. I have used pump, hot water and sodium hydroxide for several times , but no obvious improvement has occur. Is there any other solution can be done on myself?

[ballengerb1]

Stop with the chemicals and fill the sink. I know it drains slow but we must flush your chemicals before we remove the trap. Add a 1/2 cup of baking soda to that sink full of water and let it drain. Now remove the trap and carefully catch the cup of water in the trap. If the trap is clear remove the J shaped pipe going into the wall and insert a 1/4" snake into the pipe, preferable use a drum auger. Turn and push and pull, repeat until you get about 10' of snake down the drain. Reassemble and test.

[speedball1]

Bob gave you good advice. As a repair plumber I have never recommended using harsh chemicals. In your drainage system. Besides they only seem to work in TV commercials and when you try to remove the water you could burn your hands or damage your eyes.
Having said that, chances are that you'll find your clog in the horizontal line in the wall. The up side is that you'll only have to put out less then 10 feet of cable. Remove the "J" bend from the trap and send the snake up into the wall,(see image). You will run into a bend about 8 inches in but once around that it's a straight shot to the vent stack. After flush with a few tubs of hot water. Good luck, Tom