It was already after twelve minutes that the 18-year-old Icelandic Amanda Andradottir drew a shot from outside that Hannah Kohl dropped in.
A tough start for Kohl, who made his first women's league match for Hammarby.
At the end of the half, Hammarby came close to equalizing twice again.
First, Jonna Andersson finished a neat attack by shooting the ball into the goal, but it was disallowed for offside.
Then Vilde Hasund had a shot on the crossbar, but 1-0 stood at the break.,
Barely ten minutes into the second, the home team made it 2-0.
Then Kohl showed good reflexes when she saved Mia Carlsson's shot, but Tabby Tindell still put in the rebound.
With 20 minutes left, Tindell played the incoming Icelandic Emelia Oskarsdottir to make it 3-0.
Hammarby did reduce to 3-1, but it never got more exciting than that in Skåne.
After the final whistle, goalkeeper Kohl was broken and then she was comforted by her teammates.
After tonight's victory, Kristianstad is still three points from leading Rosengård.
Hammarby had needed a victory to really be close to reaching the European places that go to the top three in the women's league.