The wing is height occillation and throttle changes all the time

Hello Can anyone take a look of the flight log. and tell me why this plane act like that.

What find of hardware is this?
What plane model?
What motor? Props?
Did you tune it?
Did you read the instructions?

@amilcarlucas thank you for your reply,

1, matek765wing
2,3d printed wing GROM
3,rcinpower Smoox2806KV1350, 2blades7X4 prop
4,PID autoturned. TEC turned.
5, Yes I read. herebut not fully understand.

thanks again

I would set the speed parameters to values that correspond to your plane. Even if no airspeed sensor is present, these parameters should be set correctly, see here.

The log shows an average speed of 23m/s, a minimum speed of 17.5m/s and a maximum of 30m/s. Average speed is reached at 35% throttle, everything only roughly taken from the log.

I would set:

ARSPD_FBW_MIN,18
ARSPD_FBW_MAX,28
SCALING_SPEED,23
TRIM_ARSPD_CM,2300
TRIM_THROTTLE,35

This should work for the beginning. And then you should read more details here:
TECS (Total Energy Control System) for Speed and Height Tuning Guide — Plane documentation (ardupilot.org)

After changing these parameters you have to fly in AUTOTUNE again.

Thank you so much for your advise.

I have another same plane 5s 2507motor kv1800 7X5prop 2blades. it fly at 14-15m/s. with 20% trim throttle. This one fly too fast.