In this paper, we introduce the concept of Perfect locating signed Roman dominating functions in graphs. A perfect locating signed Roman dominating $PLSRD$ function of a graph $G=(V,E)$ is a function $f:V(G)\rightarrow\{-1,1,2\}$ satisfying the conditions that for (i) every vertex $v$ with $f(v)=-1$ is adjacent to exactly one vertex $u$ with $f(u)=2$; (ii) any pair of distinct vertices $v,w$ with $f(v)=f(w)=-1$ does not have a common neighbor $u$ with $f(u)=2$ and (iii) $f(v) + \sum_{u\in N(v)} f(u)\geq 1$ for any vertex $v$. The weight of $PLSRD$- function is the sum of its function values over all the vertices. The perfect locating signed Roman domination number of $G$ denoted by $\gamma_{LSR}^P(G)$ is the minimum weight of a $PLSRD$- function in $G$. We present the upper and lower bonds of $PLSRD$- function for trees. In addition, for grid graph $G$, we show that $\gamma_{LSR}^P(G)\leq \frac{3}{4}|G|$.