Saints were missing four Test players in Paul Sculthorpe, Francis Meli, Willie Talau and Lee Gilmour but their game was unaffected.
The visitors made an ideal start when Justin Murphy collected a fine kick from scrum-half Stacey Jones to touch down. Laurent Frayssinous added a magnificent touchline goal but Saints were not behind for long.
Sean Long wriggled over from close range for his 100th Super League score after 12 minutes, and St Helens went into the lead five minutes later when fine play from Vinnie Anderson opened up the Dragons defence to present Great Britain winger Ade Gardner with a straightforward touchdown.
Jason Hooper and Jon Wilkin combined to send Leon Pryce over for a long-range score, with Keiron Cunningham bustling over from close range to stretch the lead.
The French resistance was wilting, with Jamie Lyon then diving in to score from Long�s chip to the corner.
James Roby got in on the act with another try, but immediately from the restart the same player had his pass intercepted and Murphy made it 34-12 at the break.
Vinnie Anderson crossed for a simple score five minutes after the break as St Helens made sure.
And another Roby break was polished off by Paul Anderson�s strong run to the line, with the heavyweight prop crashing over to score under the posts.
Jamie Lyon, who this week announced he was leaving the club for Australian club Manley, completed the rout with his second touchdown.
Sean Rudder grabbed two late consolation tries and wingman Murphy completed his hat-trick for Catalans, but by that stage they were out of the match.
The match saw a Saints debut for 17-year-old centre Ste Tyrer.
St Helens: Wellens, Gardner, Lyon, V. Anderson, Hardman, Pryce, Long, Cayless, Cunningham, P. Anderson, Wilkin, Graham, Hooper. Replacements: Fa�asavalu, Fozzard, Roby, Tyrer.
Catalans Dragons: Frayssinous, Murphy, Wilson, Guigue, Verges, Rudder, Jones, Beattie, Mounis, Guisset, Hindmarsh, Fakir, Cologni. Replacements: Chan, Berthezene, Fellous, Jampy.
St Helens (34) 52. Tries: Long, Gardner, Pryce, Cunningham, Lyon 2, Roby, V. Anderson, P. Anderson. Goals: Lyon 8.
Catalans Dragons (12) 26. Tries: Murphy 3, Rudder 2. Goals: Frayssinous 3.
Referee: K Kirkpatrick (Warrington)