On the command bar, on the Relationship Types list, click the Parallel button.
Do one of the following:
If you are replacing a relationship you deleted from an existing part, select the part to be repositioned.
If you are placing a new part into an assembly, select the element on the part which you want to be parallel to a part in the assembly.
Select a part in the assembly.
On the part in the assembly, select the element to which the first part is to be parallel.
Press Enter.
Tip:
You can apply the parallel relationship with a floating offset or a fixed offset. With a fixed offset, you can type a value in the Offset Value box.
For a floating offset, you can apply an additional relationship to control the parallel offset value. For example, you can apply a planar align.