Hello, Kenyan passport issued in 2003, do I need new Kenyan passport for visa and travel to China?

How about the validity of your passport? Usually, a Kenya passport is valid for 10 years, so please check whther your passport still has a validity of more than 6 months? If yes, you can just apply for the China visa with it, and no need to apply for a new one. However, you still have to confirm this with your Entry and Exit office, since some countries requires that their must hold a passport with over one year's validity when exit the country.