Hi there moein16,
If your experiencing issues with the battery life of your iPhone, first make sure that your settings are adjusted so that you’re getting the maximum life out of your battery. There are some great tips for that on this page: Batteries - Maximizing Performance - Apple
Once you’ve implemented those tips, charge your iPhone fully and use it as you normally would over the next few days and see if you notice any improvement in the battery life.
If this continues, navigate to Settings > Battery and look over the 'Battery Usage by App' section to see which apps or services are using the most of your iPhone battery. That will help us isolate this behavior further.
Take care!