This study is a randomized, national, multicenter clinical study aimed at non-small-cell lung cancer (NSCLC) subjects with PD-L1 1% who have not previously received systematic treatment After comparing Pembrolizumab alone or Pembrolizumab combined with chemotherapy for 6 cycles, after the efficacy evaluation was stable (CR, PR, and SD), the safety and clinical efficacy of maintenance therapy every 3 weeks and every 6 weeks were compared. The eligible subjects in this study will be randomly assigned into the following two groups according to the 1: 1

(A) Standard maintenance program group, namely Pembrolizumab 200mg, every 3 weeks, a total of 2 years of treatment, followed up for 1 year; (B) Modified maintenance program group, namely Pembrolizumab 200mg, every 6 weeks, a total of 2 years of treatment, followed up for 1 year;

During the course of the trial treatment, if the subject develops disease (the first PD), the researcher will decide whether to continue the medication according to the patient's situation and communicate with the patient, and decide whether to unblind according to the specific situation, as follows: After the first PD of the subject, the researcher decides whether to continue the treatment with the original regimen according to the disease state of the subject. At least 4 weeks later, the tumor is evaluated again. If the tumor progresses again (the second PD), the subject's study treatment ends and the follow-up period is entered; if there is no progress, the original regimen is continued. If the subjects decide to continue to use Pembrolizumab-related treatment after PD, they must meet the corresponding indicators of the enrollment and exclusion criteria of this study:

1. No clinical symptoms and signs of significant disease progression (including worsening of laboratory examination results).
2. ECOG's physical performance score is stable.
3. Critical anatomical sites (such as spinal cord compression) did not see rapid disease progression or tumor progression requiring urgent alternative medical interventions.
4. The main organ function meets the corresponding laboratory indexes in the inclusion and exclusion criteria of this study.
5. The subject must sign the "Informed Consent for Continued Medication after the First Disease Progression".

The primary end point of this study was to compare the incidence of treatment-related grade 3-5 adverse events between the standard maintenance group and the modified maintenance group. The secondary end point was descriptive analysis of progression-free survival and overall survival. Using RECIST 1.1 as the evaluation standard, the independent imaging evaluation committee (IRRC) conducted the evaluation. For the first time to evaluate PD, regardless of whether they continue to study treatment after progression, the date of the first PD evaluated by IRRC will be used for all statistical analysis containing progress information.