here is the steps to jailbreak ios 8.1-8.1.X 
Step 1:
Download the latest version of Pangu jailbreak
Step 2:
Connect your device to your computer using the USB cable.
Step 3:
Enable Airplane mode, Disable Passcode from Settings > Touch ID & Passcode and turn off Find my iPhone from Settings > iCloud > Find my iPhone.
Step 4:
Please launch the application as an Administrator. Right Click on the Pangu exe and
select the “Run as Administrator” option
.
Step 5:
Pangu will take some time to detect your device. Once that is done, click on the blue “Start Jailbreak” button
.
Step 6:
Click on Already Did to proceed to the jailbreak
Step 7:
Wait for the progress bar to complete. Your iPhone or iPad will reboot.
Step 8:
Once the process completes, you should see the Cydia icon on your home screen
After the jailbreaking process is complete, do not forget to checkout our article on tips to keep your jailbroken device secure.
also checkout this artical ,How to fix problem in jailbroken your idevice
VIDEO TUTORIAL:
Step 1:
Download the latest version of Pangu jailbreak
| Source | OS | Version | Download URL |
|---|
| 25PP | Windows | 1.2.1 | http://adf.ly/1WOj5N |
| MEGA | Windows | 1.2.1 | http://adf.ly/1WOjB0 |
| 25PP | Mac | 1.0.0 | http://adf.ly/1WOjIH |
| MEGA | Mac | 1.0.0 | http://adf.ly/1WOjMC |
Connect your device to your computer using the USB cable.
Step 3:
Enable Airplane mode, Disable Passcode from Settings > Touch ID & Passcode and turn off Find my iPhone from Settings > iCloud > Find my iPhone.
Step 4:
Please launch the application as an Administrator. Right Click on the Pangu exe and
select the “Run as Administrator” option
.
Step 5:
Pangu will take some time to detect your device. Once that is done, click on the blue “Start Jailbreak” button
.
Step 6:
Click on Already Did to proceed to the jailbreak
Step 7:
Wait for the progress bar to complete. Your iPhone or iPad will reboot.
Step 8:
Once the process completes, you should see the Cydia icon on your home screen
After the jailbreaking process is complete, do not forget to checkout our article on tips to keep your jailbroken device secure.
also checkout this artical ,How to fix problem in jailbroken your idevice
VIDEO TUTORIAL: