When I double click the side button of my watch, no respond

Hi lifei225,

Thanks for posting in Apple Support Communities.

We understand that double-clicking for the side button isn't always working. This could be due to debris or that you have Water Lock enabled.

Clean and dry your Apple Watch

Keep your Apple Watch clean and dry. Soaps, cleaning products, abrasive materials,* compressed air, ultrasonic cleaning, and external heat sources can cause damage and shouldn't be used with your Apple Watch. 

To clean your Apple Watch, follow these steps:

1. Turn off your Apple Watch and remove it from the charger.

2. If you have a leather band, remove it from your Apple Watch.

3. Wipe your Apple Watch clean with a nonabrasive, lint-free cloth. If necessary, lightly dampen the cloth with fresh water. If your Apple Watch has substances or debris visible in places such as the speaker ports, you can hold your Apple Watch under lightly running, warm, fresh water until it's clean. Soaps and other cleaning products shouldn’t be used.

4. Dry your Apple Watch with a nonabrasive, lint-free cloth, including the surface of the back crystal.

Find these tips and more about cleaning your Apple Watch in How to clean your Apple Watch - Apple Support.

How to turn off Water Lock and eject water

Press and hold* the Digital Crown on the side of your Apple Watch until the display says Unlocked. A series of tones plays to clear any water that remains in the speaker, and then you can use your display as usual.

* If your Apple Watch has watchOS 8 or earlier, rotate the Digital Crown instead of pressing it. 

How to use Water Lock and eject water from your Apple Watch - Apple Support

Regards.