  We fully solve the long-standing problem of operator basis construction for
fields with any masses and spins. Based on the on-shell method, we propose a
novel method to systematically construct a complete set of lowest dimensional
amplitude bases at any given dimension through semi-standard Young tableaus of
Lorentz subgroup $SU(2)_r$ and global symmetry $U(N)$ ($N$ is the number of
external legs), which can be directly mapped into physical operator bases. We
first construct a complete set of monomial bases whose dimension is not the
lowest and a redundant set of bases that always contains a complete set of
amplitude bases with the lowest dimension. Then we decompose the bases of the
redundant set into the monomial bases from low to high dimension and eliminate
the linear correlation bases. Finally, the bases with the lowest dimension can
be picked up. We also propose a matrix projection method to construct the
massive amplitude bases involving identical particles. The operator bases of a
generic massive effective field theory can be efficiently constructed by the
computer programs. A complete set of four-vector operators at dimensions up to
six is presented.
