Is there any other solution to root this phone ? Apk or pc program?
Unfortunately not. 5.1+ MediaTek generally requires flashing a TWRP or pre-rooted ROM.
You can try that one. We will put up a safe Elephone M3 TWRP link in a moment. But it's untested. So you are the guinea pig. There's no official link to this on Needrom. Just the direct download link from that clickjack blog.
You will need to flash it through fastboot. You can boot it instead of flashing it, so it won't actually replace the recovery on your phone.
Follow this video tutorial from GizBeat, but probably don't need to unlock the bootloader. If the bootloader is locked, it won't allow the flash anyways.
Download Elephone M3 TWRP custom recovery: [Only registered and activated users can see links Click here to register] [Only registered and activated users can see links Click here to register]