Modeling and simulation of TiO2 nanorod based DSSC is done to explore the effect of nanorod diameter on the short-circuit current density. The model could be validated by simulation software TiberCAD and the experimental results. The results show that the porosity decreases with increasing diameter of nanorod for fixed value of inter-rod separation. The short-circuit current density can be improved by optimizing the nanorod diameter. From this study it could be observed that the nanorods of diameter from 65 nm to 90 nm with porosity range from 0.43 to 0.66 would result in best performing DSSC.