how to place object in middle illustrator

Select the object, open the Align panel, set it to Align to Artboard , then click Horizontal Align Center and Vertical Align Center to place it in the middle of the artboard.

Quick steps

1. Select the object.
2. Go to Window > Align if the panel is not already visible.
3. In the Align panel, choose Align to Artboard.
4. Click Horizontal Align Center.
5. Click Vertical Align Center.

These steps center a single object on the page/artboard in Illustrator.

If you mean between objects

If you want an object centered relative to other objects, Illustrator also supports aligning to a selection or a key object instead of the artboard.

For multiple objects that should stay together, group them first, then align them as one unit.

Tiny example

If you have a logo and want it dead center on a poster, select the logo alone, switch Align to Artboard , and use the two center buttons.