How to smooth the connection of 2 splines

[majianjia]

In sketch, they are already connected (the control points).

[jeff_strater · Accepted solution]

for tangent continuity, use a Tangent constraint.  For curvature continuity, use a Curvature constraint:

[davebYYPCU]

Add Tangent or Curvature Constraints 

and check the alignments with Curvature Combs, adjusting for smooth with tangent handles.

Might be better for one spline

Might help...

[majianjia]

Thank you very much for your reply. It is working now