Downey and Ireland team-mate Felix English from Brighton claimed victory with 57 points.
The Irish team pairing saw off runners-up Denmark and New Zealand in third.
In the Colombian round of the World Cup earlier this month, Dromore man Downey won the points race and came second with English in the 30k Madison.
Downey's next target will be the World Championships in Hong Kong in April.
County Down's Mark Downey has secured another UCI World Cup gold medal by winning the Madison race at the UCI Track Cycling World Cup in Los Angeles.