Download Onda V989 Octa Core Root Tool from here or from here.
Unzip it after download. Root Tool archive contains Update.apk & ondaos_V989_Root.zip
1. Install update.apk, copy ondaos_V989_Root.zip to your SD card
2. Find and launch Update application, choose Local Update, find the ondaos_V989_Root.zip in the sdcard or extsd.
ADS HERE !!!