Defect dark solitons were numerically researched in parity-time-symmetric optical lattices with an additional defect in the real part. When the diffraction is balanced with the self-defocusing nonlinear effect,dark solitons can be obtained. When a defect is added in the real part of parity-time-symmetric optical lattices,defect dark solitons can also be obtained. Numerical results showed that defect dark solitons can exist and be stable in large parameters range. The strength of additional defect has a maximum value,and the defect dark solitons do not exist above this value. The amplitude of the imaginary part of parity-time-symmetric optical lattices can affect the stability of the defect dark solitons.