Objective To explore correlations between saccades and gait adaptability of patients with Parkinson disease（ PD） at early to middle stage under complex walking environment， then make further investigation on cognition affecting saccades. Methods A total number of 53 early to middle stage PD patients from Parkinson Medical Center of Beijing Rehabilitation Hospital from April 2019 to November 2019 and 25 healthy controls（ HCs） were recruited. The general clinical information of the subjects was collected， and the cognitive function of the patients was evaluated by Mini-Mental State Examination（ MMSE）， Montreal Cognitive Assessment Scale（ MoCA）， Boston Naming Test（ BNT）， clock drawing test（ CDT） and Trail Making Test Parts A & B（ TMT-A/B）. All subjects underwent saccade tests by videonystagmography and six-item walking adaptability test（ C-Gait） by treadmills augmented with visual targets and obstacles（ C-Mill）. Results Compared with the control group， the average saccade movement latency prolonged and the average saccade speed slowed down in the PD group， however the difference was not statistically significant［ 222.45（ 190.47， 249.94） ms vs（ 220.83±36.86） ms； 416.05（ 362.29， 452.63）° /s vs（ 428.13±44.95）° /s； P＞ 0.05］. The saccade latency of the PD group was negatively correlated with the slalom task performance（ t=-2.282，P=0.027） and obstacle avoidance task performance（ t=-2.700， P=0.010）， with statistical significance. The time of TMT-A was correlated with saccade latency（ t=3.708， P=0.001）， with statistical significance. Conclusions The prolongation of saccade latency in PD patients is related to abnormal gait adaptability， and is one of the important factors affecting gait adaptability. The executive dysfunction in PD patients may influence the saccade latency.