The coupled equations for the incoherent optical spatial solitons in a nonlocal nonlinear medium is studied analytically. With the soliton solutions hereby obtained via the symbolic computation, the optical-soliton motion in the nonlocal nonlinearmedium is studied: |psi| is inversely related to kappa, omega, and n(0), while Delta n is positively related to omega and n(0), but Delta(n) is independent of kappa, with psi as the slowly varying amplitude of the beam, Delta n as the refractive index change, kappa as the beam intensity distribution, omega as the frequency of the propagating beam, and n(0) as the unperturbed refractive index. Head-on and overtaking interactions are observed, and head-on interaction is transformed into an overtaking one with. increasing. Bound-state interaction is displayed, and with n0 increasing, the period of. decreases, while that of Delta n increases. Considering the external forces in the nonlocal nonlinear medium , we explore the chaotic motions in the nonlinear nonlocal medium, including effects of the external forces on such motions. It is seen that when vertical bar alpha(1)vertical bar >>vertical bar 2 omega(2)n(0)/c vertical bar and vertical bar alpha(2)vertical bar >>vertical bar kappa vertical bar, the two-dimensional attractors with stretching-and-folding structures are exhibited, and the developed chaos occurs, where alpha(1) and alpha(2) are the amplitudes of external forces, c is the speed of light in vacuum. Such chaotic motions are weakened with omega, kappa,(omega) over bar (1) and (omega) over bar (2) increasing, or with n(0) decreasing, where (omega) over bar (1) and (omega) over bar (2) represent the frequencies of external forces.