The structure, magnetic and transport properties of La1−xNaxMnOz manganese perovskite prepared by Pechini process were investigated. Low field magnetoresistance in temperature range from 77 K to Curie temperature was obtained and two obvious peaks were observed in the resistivity versus temperature curves. Differential scanning calorimetry results show that the broad bumps far below Curie temperature does not originate from anomalous phase transition. The effect of annealing is carefully investigated and the results indicate that oxygen inhomogeneous distribution may be the main reason for the curious behaviors.