Hi,Should I split height field to serveral parts by heightfield_tilesplit node When deal with high resolution ?

Sure, it can be useful, especially if your terrain has an irregular shape where a large square creates wasted space.

Creating a large low resolution heightfield to get your basic shapes, then splitting it in tiles, resampling them as needed according to their distance form camera, for instance, and creating detail and refining your terrain where it's going to be noticed, can be a good way to go.