A signed 3-partite graph is a 3-partite graph in which each edge is assigned a positive or a negative sign. Let G(U, V, W) be a signed 3-partite graph with $U;=;{u_1,;u_2,;{cdots},;u_p},;V;=;{v_1,;v_2,;{cdots},;v_q};and;W;=;{w_1,;w_2,;{cdots},;w_r}$. Then, signed degree of $u_i(v_j;and;w_k)$ is $sdeg(u_i);=;d_i;=;d^+_i;-;d^-_i,;1;{leq};i;{leq};p;(sdeg(v_j);=;e_j;=;e^+_j;-;e^-_j,;1;{leq};j;{leq}q$ and $sdeg(w_k);=;f_k;=;f^+_k;-;f^-_k,;1;{leq};k;{leq};r)$ where $d^+_i(e^+_j;and;f^+_k)$ is the number of positive edges incident with $u_i(v_j;and;w_k)$ and $d^-_i(e^-_j;and;f^-_k)$ is the number of negative edges incident with $u_i(v_j;and;w_k)$. The sequences ${alpha};=;[d_1,;d_2,;{cdots},;d_p],;{eta};=;[e_1,;e_2,;{cdots},;e_q]$ and ${gamma};=;[f_1,;f_2,;{cdots},;f_r]$ are called the signed degree sequences of G(U, V, W). In this paper, we characterize the signed degree sequences of signed 3-partite graphs.