My passport is Sri Lanka Iam going to Sri Lanka by china eastern airlines via Shanghai.can I get 24

Wijendra, if you are flying from a some country different than Sri Lanka to Shanghai and from there to Sri Lanka and your total layover (transit time) is shorter than 24 hours, you are definitely eligible for 24 hour visa free transit and you do not need any kind of visa.

If you plan to exit the airport and your transit time in Shanghai is longer than 9 hours, the first thing you will do is to approach 24/144 hour visa free transit counter where you will apply for a temporary entry permit in order to be allowed to exit the airport. This application is free of any charge and here you will present your flight tickets and your accommodation booking confirmation if your layover is during the night hours. After a short check and a decision making your permit will be granted and you head to the immigration to spend some time in exploring the city. However, if your layover is up to 9 hours long, you should not even try to apply for a temporary entry permit because it will be rejected and you will wait for your flight to Sri Lanka airside (in the transit area). I wish you a pleasant journey.