My Apple Watch continuously enters the SOS status (alarming & counting down from 3 to call the Police/Medical Service/Emergency Contact) while all of my conditions are fine. Is there any problem with the SOS trigger and how to solve it?

Hi

With the "Hold to Auto Call" option enabled, Emergency SOS activates if the side button is pressed and held down:

About SOS on Apple Watch - Apple Support

It is possible that you are activating the feature accidentally. If so:

It may help to adjust how you are wearing your Apple Watch:

• If your Apple Watch is worn too close to your hand, then the side button may be pressed and held down by the back of your hand when flexing your wrist.
• It may help to wear your Apple Watch a little further up your arm.
• It may otherwise help to wear your Apple Watch with the buttons on the other side and/or on your other wrist:
  • To change the configuration: on your iPhone, in the Watch app, go to: My Watch (tab) > General > Watch Orientation > choose the preferred wrist and side for the buttons.

To turn off the "Hold to Auto Call" option, if desired:

• On your iPhone, in the Watch app, go to: My Watch > General > Emergency SOS - turn off Hold to Auto Call.

The following steps may otherwise help (check after each):

If you have not yet done so, it may also help to update your iPhone and Apple Watch to the latest software, starting with your iPhone:

• Update the iOS software on your iPhone, iPad, or iPod touch - Apple Support
• Update the software on your Apple Watch - Apple Support

Close the Watch app and restart both your iPhone and your Apple Watch:

• To close the Watch app on your iPhone:
  • Double-click the Home button, then swipe up on the app preview.
• Turn both devices off together, then restart your iPhone first:
  • Restart your iPhone, iPad, or iPod touch - Apple Support
  • Restart your Apple Watch - Apple Support

Unpair and re-pair your Apple Watch:

• The Watch app on your iPhone takes a backup of your watch automatically when unpairing via the app.
• Initially choose to Restore from Backup during set up (most data and settings will be restored, with some exceptions, such as Apple Pay cards, passcode).
• If the issue persists, consider instead unpairing and setting it up as a new watch.
• Unpair your Apple Watch and iPhone - Apple Support
• Set up your Apple Watch - Apple Support

If the issue persists, then I suggest that you contact Apple Support (mail-in service may be available, if required), make a Genius Bar reservation or visit an Apple Authorised Service Provider with a view to arranging for your watch to be inspected and, if recommended, serviced:

• Contact - Official Apple Support
• https://twitter.com/applesupport
• http://www.apple.com/retail/geniusbar/
• https://locate.apple.com