could you provide some log file?

Maybe you can provide more details (a log file), so we can analyze what happened.

Please refer to this for a quick start:
https://openimu.readthedocs.io/en/latest/apps/ins.html
Unless you have no other choice, don't use NMEA. For ublox, we support nav-pvt. You can config your unit to output and only output ublox binary nav-pvt. If you have to use NMEA, you need to config the unit to output GGA, VTG and RMC.
There are also other posts in the forum about INS. You could also first search in the forum.

First, openRTK is a different hardware unit. You can contact sales (leave a message on www.aceinna.cn) to see if you can buy one.
Or, you can try OpenIMU300ZI which has an INS app.

Which unit are you using, OpenIMU330BI or OpenRTK330? OpenIMU330BI does not have an INS app now.

@John-Xie , The system seems working. However, if you are using an old version of the firmware, I would suggest you updte to the latest firmware via the Aceinna extension because there are many updates.

@John-Xie , is there any luck?

@John-Xie , please notice UBLOX_BINARY indeed means uBlox binary nav-pvt.

First, please check your receiver output baud rate and protocol. The protocol should match that in UserConfiguration.c.
Further, you may print log in EKF_SetInputStruct() in EKF_Algorithm.c to see if GPS measurement is fed into the algorithm. If not, you need check the GPS driver in taskGPS.c.

这个资料很多啊，比方说：Shin - 2001 - Accuarcy improvement of low cost INSGPS for land .pdf