Bode Miller -- Custody War Demands ... Against Alleged Baby Mama

Olympic skiing champ Bode Miller wants to be in his son's life ... so much so, he's asking a judge to force his new baby mama to bring the kid back to California.

TMZ broke the story ... Bode's been battling Sara McKenna since filing a paternity suit demanding shared custody of their one-month-old son. McKenna has claimed Bode's a terrible dad ... who asked her to abort the child.

Bode insisted he has a good track record as a dad ... citing his relationship with another child, from a previous relationship.

Now, Bode has filed docs, asking a judge order Sara to take the baby out of New York ... and return to San Diego, where Bode lives. He also wants an order stating she needs written consent, if she wants to take the kid out of CA.