how to draw a plane in the centre of the hole or cylinder in solidworks?

Multiple ways to create it, here is one method:

I would make the sketch visible that you used for the cut. Then I would create a new plane, and constrain it to be parallel to the previous plane, and coincident with the centerpoint of the circle used to cut the cylinder. This uses the "Parallel plane at point" constraint.

i hope that will help you

Hai Arul

1). Select "Plane" from "Reference Geometry" in "Features" Bar.
2). Click on cylinder one side cross section face.
3). Click on cylinder another side cross section face.
4). Done.

just check it that "plane" option is on or not in "View" manu.

A variant to MF's answer above:

1). Go to Reference Geometry and select Point
2). Select Center of arc
3). Click on the hole or circular feature you want to place the plane through.
4). A point is placed... Do not de-select.
5). Go to Reference Geometry and select Plane.
6). The Point is already selected as the plane's first reference, now
select a second and possibly a third reference.

One method I use most of the time is to:

- Turn on visibility for Temporary Axes
- Reference Geometry -> Plane
- Click the temporary axis and a second geometry.

Using this method the plane is constricted in one direction (through
the axis) and the Feature Tree will have fewer rows.