For a sequence {Mn}∞n=1{Mn}∞n=1 of expanding matrices with Mn∈Md(ℤ) and a sequence {Dn}∞n=1 of finite digit sets with Dn⊂ℤd, the Moran measure μ{Mn},{Dn} is defined by the infinite convolution
μ{Mn},{Dn}=δM−11D1∗δM−11M−12D2∗δM−11M−12M−13D3∗⋯
and the convergence is in the weak sense. Under some additional assumptions, we show that L2(μ{Mn},{Dn}) contains an infinite orthogonal set of exponential functions if and only if there exists an infinite subsequence {nk}∞k=1 of {n}∞n=1 such that (M∗nk+1M∗nk+2⋯M∗nk+1Znk+1)∩ℤd≠∅
for any k∈ℕ+, where Znk+1:={x:∑α∈Dnk+1e2πi〈α,x〉=0}∩[0,1)d. This extends the results of [J. L. Li, A necessary and sufficient condition for the finite μM,D-orthogonality, Sci. China Math. 58 (2015) 2541–2548].