Using parafermionic field theoretical methods, the fundamentals of 2d
fractional supersymmetry QK=P are set up. Known difficulties
induced by methods based on the Uq(sl(2)) quantum group representations
and non commutative geometry are overpassed in the parafermionic approach.
Moreover we find that fractional supersymmetric algebras are naturally realized
as matrix models. The K=3 case is studied in details. Links between 2d
(31,0) and ((312),0) fractional supersymmetries and N=2
U(1) and N=4 su(2) standard supersymmetries respectively are exhibited. Field
theoretical models describing the self couplings of the matter multiplets
(02,(31)2,(32)2) and (04,(31)4,(32)4) are given.Comment: Latex,no figure,17page