Although spin excitations in BaFe2As2 are thought spin-wave excitations and the excitation will locate at antiferromagnetic vector (1 0) only for a detwinned sample, the real situation is more complicated. Since high-energy spin waves in the orthorhombic phase below TN in BaFe2As2 are rather similar to high-energy spin excitations of tetragonal BaFe1.9Ni0.1As2 and high-energy spin excitations do not seem to change across TN, it would be interesting to ask if the high-energy spin excitations in orthorhombic BaFe2As2 are coming from twinning effect as suggested from Heisenberg spin wave model or have nothing to do with the orthorhombic underlying lattice. The only way to conclusively address this question is carry out spin wave measurements using detwinned BaFe2As2 single crystals.Here we propose to measure the spin waves of detwinned BaFe2As2 by time of flight spectrometry.