Solution: (1)∵ parabola y=-? (x+3) (x- 1+m) (m < 0) intersects with the X axis at points A and B, and intersects with the Y axis at point C.

When y=0,-? (x+3)(x- 1+m)=0, and the solution is x=-3 or x =1-m.

When x=0, y=-? X3(- 1+m)，y = 3/2-3/2m。

∴ A (-3,0), B (1-m,0), C (0.3/2-3/2m)

(2) The area of ∫△ ABC is 2 1, that is,1/2 (1-m+3) (3/2-3/2m) = 21,and the equation can be simplified as follows

m？ -5m-24=0。

M=-3 or m = 8 (m < 0, so it is removed).

∴m=-3, then the functional relationship is y=-? (x+3)(x- 1+-3), i.e.

y=-？ x？ +? x+6