Cartesian product of two set A and B is given as:
AxB = { (a,b) | a$\epsilon$A $\Lambda$ b$\epsilon$B }
Now we have A as empty set and B as the non-empty set. therefore there is no element a such that a$\epsilon$A satisfies, due to which the condition a$\epsilon$A $\Lambda$ b$\epsilon$B fails.
so we can conclude that AxB would also be an empty set.