In this paper, we study the existence of multiple positive periodic solutions for the second order differential equation x′′(t) + p(t)x′(t) + q(t)x(t) = f(t,
A Riesz type product as Pn=multiply from j=1 to n(1 + aω j + bω j+1 ) is studied,where a,b are two real numbers with |a| + |b| < 1,and {ω j } are independent