We prove norm inflation and hence ill-posedness for a class of shallow water wave equations, such as the Camassa-Holm equation, Degasperis-Procesi equation and Novikov equation etc., in the critical Sobolev space H 3/2 and even in the Besov space B 1+1/p p,r for p ∈ [1, ∞], r ∈ (1, ∞]. Our results cover both realline and torus cases (only real-line case for Novikov), solving an open problem left in the previous works ([5, 14, 16]).