Abstract: In order to explore the potential application of ⁹⁹Tc^m labeled mannosylated dextran conjugates with amine-pyrazole group (Dextran-amine-pyrazole-mannose, DPZM) as sentinel lymph node (SLN) imaging agent, ⁹⁹Tc^m labeled DPZM conjugates (DPZM-4 and DPZM-8) were prepared through ⁹⁹Tc^m(CO)₃⁺ precursor synthesized from Isolink kit, and the invivo biological behaviors of ⁹⁹Tc^m-(CO)₃-DPZM conjugates were investigated. The labeling yields of ⁹⁹Tc^m-(CO)₃-DPZM conjugates were above 90%, and the labeled conjugates were relatively stable in vitro and in vivo. The biodistribution results demonstrated that ⁹⁹Tc^m-(CO)₃-DPZM conjugates were accumulated mainly at injection sites and SLNs, the highest uptake in SLN was found to be 6.31%ID 1 h p.i. and no significant uptakes were found in major organs such as liver and spleen. The biodistribution of these conjugates was also sensitive to the injected dosage, the uptake of SLN and PE% increased while the injected dosage decreased. The results of SPECT imaging study corresponded to those of biodistribution study, SLN can be clearly visualized and better images could be obtained at lower dosages. the high SLN uptake and PE% along with low radioactivity background of ⁹⁹Tc^m labeled DPZM conjugates showed promise for SLN imaging and detection.