Based on the design of proportional and derivative (PD) observers, a new parametrization of all observers for descriptor systems is developed. Without using any additional transformations, the present observer parametrization is convenient and efficient to be performed. The connections between the proposed parametrization and the known results are established. For descriptor systems with bounded input disturbances, the estimation error dynamics are parametrized with respect to the disturbance vectors. An example is included to illustrate the parametrization procedures.